About this time two years ago, USC defensive lineman Jacob Lichtenstein couldn't figure out what was wrong with his calf muscle as he just kept re-injuring it from the summer on through the first half of the season. It made him at least consider whether he would even play football again for the Trojans.

Whether he should even keep trying.

On Saturday, after two lost seasons, many unexpected setbacks and a whole lot of patience, Lichtenstein notched the first two sacks of his collegiate career in USC's 37-14 win at Colorado.

"To be honest, back through that time, 2018-2019, I definitely had thoughts of maybe medically retiring. It’s such a blessing to be healthy and be back here and those thoughts are completely gone," Lichtenstein said after practice Wednesday. "Just loving football and just love being out here with my guys. It’s been a journey."

To say the least.

Lichtenstein signed with USC as a three-star defensive lineman in the 2017 recruiting class out of Weston, Fla.

He redshirted that first season, actually played 11 games with two starts back in 2018, totaling 15 tackles and 2 tackles for loss, and everything to that point had been on comfortable trajectory.

What followed was anything but.

Lichtenstein had offseason cartilage surgery in his knee that year, which would lead into a lost 2019 season. He later needed surgery for a sports hernia as well.

Then the pandemic hit and the 2020 Pac-12 season was initially cancelled. Lichtenstein became one of a few Trojans to choose to opt out once the season was back on track.

All told, he went a little less than three years between games, and has been through three defensive line coaches and plenty of self doubt along the way.

But that only makes him appreciate this season even more.

"It’s definitely a journey. There’s been tons of ups and downs. But I couldn’t be more proud of myself for being here today, sticking through it all and fighting through adversity," he said. "So I’m really happy with how everything has went. I wouldn’t take anything back."

Lichtenstein is asked about his comment about considering a medical retirement from football and how close he ever truly got to that point.

"Not super close, but it definitely popped into my head. I’m just happy to be out of that place," he said.

Eventually, Lichtenstein would get diagnosed with compartment syndrome in his calf, but it took five or six months to figure out what was going on, he said.

He first pulled the calf muscle in the summer of 2019 and wouldn't have surgery until that December. In between, it was just consistent frustration.

"I had a great spring, I started summer, then I kind of just messed up my calf and just kept re-messing it up. During the season, probably like Week 5 – because we kept trying to come back, like, we’re not gonna call this season quits so we’re going to keep trying to rehab it -- about like the fifth time or fourth time I pulled my calf, they told me it was done," he recalled. "I had to think about what I was going to do, how I was going to rehab this, how are we going to approach this surgery? What are we going to do? That was a tough point. I didn’t really know what the future held. ...

"That summer when I kept pulling it over and over again and going through such a dark mental period and just not knowing what's wrong with it -- like it just keeps pulling, it keeps pulling -- and then we finally get a surgery and it starts feeling better and better. It was a long recovery."

Compartment syndrome is essentially a buildup of pressure in the muscle that can lead to greater complications, and in Lichtenstein's case he needed a fasciotomy, which involves cutting into tissue in the affected area to relieve pressure. Fellow USC defensive lineman Ishmael Sopsher had a similar procedure done before spring practice and is still not fully practicing.

Lichtenstein said the rehab was unlike anything he had gone through with his knee scope or hernia surgery and that it took a full year for him to feel close to 100 percent again.

Then came the pandemic and an uncertain 2020 football season. With all classes online and moving close to obtaining his degree, Lichtenstein decided to head back to Florida and leave football behind at least temporarily.

"It was just a lot of uncertainty at the time and I was finishing up my degree. I just felt like it was, I don't know about a good time, but I felt like it was the right thing to do to just finish up my academics and just focus on that with how much uncertainty was going on," he said, looking back on that move.

"... Most of these players are from California and if something goes wrong or like we couldn't use the weight room, a lot of these people have resources out here in California and I just didn't have that because a lot of my connections are in Florida ... so just not having those same resources that my teammates had it kind of made it tough. But there wasn't one thing that solely made me opt out. There was a lot of things. It was a combination."

During that time back home, though, Lichtenstein was working out about three hours a day, split over three separate periods, he says, eating a lot of organic food and benefitting from being the son of a personal trainer.

"My mom, she's a former figure competitor. She used to get on stage and compete, like, [IFBB] Pro, whatever. So now she's a personal trainer. So I would go to the gym every morning with her at like 7, do my own training and then run in the afternoon and make sure I'm getting a lot of sleep," he recalled. "She cooks really well, too, so she was just making sure my nutrition was spot-on. So I saw a lot of gains definitely in that time."

He also saw his Trojans teammates winning games on Saturdays during the delayed pandemic-shortened season last fall.

USC defensive line coach Vic So'oto called Lichtenstein to see if he wanted to reconsider his opt-out decision, and soon enough he was back with his teammates reacclimating to the program for the final two weeks of the season.

"Just watching my guys out there and not being there, it definitely hurt. And it was around the end of the semester, end of classes, and Coach Vic called me and was just like, you know, we could really use you and whatever. So I just wanted to come back out and help my team," Lichtenstein said. "That conversation with him definitely kind of sparked something in me, like, damn, I need to get back with my team. I have no reason not to be over there. So I finished the school, because like I was saying before, partially some of the reason why I took off was just to clear my academics and make sure my academics were straight. And then classes ended so I had nothing else to do except come back here and help the team. So that made it easy."

While Lichtenstein didn't get into those final games at all, his return set the foundation for what is happening now.

He recalls that he lost 10 pounds during his training back in Florida, getting down to 255 pounds, while all the while gaining strength and getting his squat up to 450-465 pounds. Since rejoining the program, he's pushed his weight up to 270 per the roster.

"He’s gotten so much better from the spring. He’s night and day, night and day. He’s big and strong now," defensive coordinator Todd Orlando said earlier this fall. "I thought he was a little lean when I first got here. ... Then he turns into 275, and he’s kind of got a mindset of, I might have the opportunity to maybe play at the next level, and I’m gonna change my body and get a little heavier and start doing the stuff that Vic wants him to do."

While Lichtenstein's emergence this season has perhaps exceeded the expectations of many observers of the program, Orlando and So'oto say they aren't surprised.

"I didn't know him that long ago, I just know what he's done here, and what's he done is showed up everyday and got after it," So'oto said after a practice last month. "He's showed a lot of good stuff, but a lot of what was expected of him because of what he's done on this field."

On the second play of Colorado's second possession Saturday, Drake Jackson came racing around the right tackle, eventually forcing quarterback Brendon Lewis to step up into a collapsing pocket where Lichtenstein came off his block and brought the QB to the ground for his long-awaited first career sack.

He wouldn't have to wait all that long for the next one.

Later in the fourth quarter, on Colorado's final offensive play of the game, Lichtenstein easily beat his blocker from his interior defensive tackle spot and got Lewis down again.

Just like that, the payoff for his patience in overcoming two full seasons without playing in a game realized with the first two sacks of his collegiate career.

"It means everything, you know? Like you said, being away from the game for three years, my last season playing was 2018, so I feel like just being away from the game for that long, it really just builds so much love inside me for it," he said Wednesday. "I just don't take it for granted, so yeah it meant everything to me and excited to build off that."

With USC's depleted defensive line depth, Lichtenstein emergence in this his fifth year in the program has been crucial.

He played 43 out of 58 defensive snaps for USC on Saturday -- tied for most on the defensive line with Tuli Tuipulotu, who was able to slide outside to the edge more than he has earlier this season. Lichtenstein has at times worked in behind Tuipulotu at that three-technique defensive tackle spot, but there is enough rotation up front that he's played a significant number of snaps in each game so far, including 50 out of 57 snaps vs. Stanford and 52 out of 76 snaps vs. Oregon State.

"Jake's a guy who's always had all the physical tools, just with his size and how big he is and he's a guy that can play on the edge but he's also a guy that can play on the interior," interim head coach Donte Williams said. "Last year I think he had a little bit of issues, in the spring he didn't know how to fight and battle through those particular injuries. You play D-line you're always going to be beat up, right? Now Jacob no matter what's going on he pushes and fights through, and it's paying off. It paid off for a big game this past Saturday and I look forward to that role continuing to grow because he has the size, he has what you want in a defensive lineman with the twitch and everything else. Shoot, Coach Vic is coaching the hell out of him."

Said So'oto: "He’s been consistent every day. He’s been out here. He’s practiced through things that he would usually pull himself out of, and it’s starting to pay off."

The only consistency for two long years for Lichtenstein was a string of setbacks and obstacles.

That's all behind him now. As for the future, he's not sure. He has the eligibility to return next season but hasn't made any final decisions.

He's just enjoying this experience and everything he had been waiting for and working toward for so long.

"It was awesome," Lichtenstein said, going back to the two-sack performance Saturday. "Like we've been talking about, three years away from the game, that's a lot of time and a lot went through my head and it was amazing. It keeps adding to the confidence, adding to everything.

"[I got texts and calls from] family, friends, everything, all just congratulating me, mostly for fighting through adversity just because it takes a lot. You could think your career is over and then just have that mental switch like, nah, I'm not going out like that, I can fix this. And it's fixed."