Justin Trattou isn't bringing an old-school mentality to his physical therapy anymore.

After his second of five NFL seasons was derailed by more ankle and foot injuries in 2015, the Vikings reserve defensive end swapped some of his hard work for work smart. That's not always natural for an undrafted player like Trattou, whose best asset is a "warrior" approach, as fellow end Brian Robison described.

Trattou was a barefoot warrior this offseason, mixing in workouts designed to strengthen his lower legs "as opposed to just pounding weights."

"Trying to build up the muscles in my feet, because I had some pretty serious injuries," Trattou said. "Getting smarter as I get older and so far I've felt pretty good."

Not many players last in the NFL by appearing in 21 games over five seasons. Though not many snatched two interceptions in 22 snaps last year, either.

The 27-year-old Trattou continues to seize his limited opportunities in Minnesota, where he remains a relative unknown despite being here since 2013.

He's only two years removed from not making the Vikings final roster, threatened to become the latest in the defensive roster churn under head coach Mike Zimmer. He spent 13 weeks on the practice squad before an injury created an opening.

Injuries. They can give, but they take plenty.

Trattou flipped a strong 2015 preseason into a roster spot, eventually earning a rotational role by Week 2 — when he dropped into coverage and intercepted Detroit's Matthew Stafford. The next game, Trattou suffered the foot injury that put him back on the sideline for 10 weeks.

Another NFC North foe in Jay Cutler would be intercepted upon Trattou's return in Week 15.

"He's a warrior every day no matter what he feels like," said Robison, who himself practiced with an illness this week. "He's going to come out here and give you everything he's got. That's what we ask out of guys."

Two picks in 22 snaps, which is just a decent Sunday's work for a normal rotational lineman. It was enough for the Vikings to re-sign him to a one-year, $760,000 deal this spring. Now he's gunning for that rotational spot again in a deep and talented defensive line.

Even if he is the fourth defensive end on the roster, history shows opportunities arise quickly.

"The next step for me is just continuing on with the preseason into the regular season," Trattou said. "I want to be out there in the regular season getting sacks, making plays."

His limited highlight reel and no quit haven't gone unnoticed by teammates and coaches. Trattou led all Vikings defensive linemen with 39 snaps in last week's preseason opener in Cincinnati.

Against the Bengals, Trattou teamed with Tom Johnson on a twist that landed his first sack of the preseason, giving him 6.5 sacks in the last 14 exhibitions.

"A couple years ago, he wasn't going to make the team," Zimmer said. "It's a good lesson for a lot of young guys…If you keep working, fighting, keep trying to do your best and stay in the right system and listen to the coaches, good things end up happening for you."