Brian O'Neill left his exit interview with Vikings coaches after the 2018 season with marching orders. Those orders led the right tackle directly into weight rooms and cafeterias this offseason.

Morning workouts in Orange County were followed by position-specific drills in sunny afternoons, to best mimic training camp conditions. There were the 2½-hour high-intensity training sessions with University of Pittsburgh strength coach Dave Andrews, again "in the middle of the heat," while following a meal plan that reached 6,000 calories per day.

O'Neill tipped the scales at 301 pounds — up about 6 pounds from last season — this week in Eagan, where he has given the Vikings offensive line a promising bookend. One month before his second NFL season, O'Neill is fixated on establishing himself as a 6-7 bouncer among bullies, pushing the Vikings and its beleaguered offensive line to more wins.

Ice cream containers, so far, are winless.

"Last year, I was [eating] about a pint a night," O'Neill said.

He was a 240-pound tight end converted to offensive tackle four years ago when he woke in the middle of the night to eat — "That's when I was trying to gain like 50 pounds in a couple of months."

Growth is more gradual these days. O'Neill says he is only halfway toward his muscle-building goal. He wants to add another 5 to 6 pounds.

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Video (05:15) Reporters Ben Goessling and Andrew Krammer examine the defense and the potential problems that may lie ahead.

Weight should complement O'Neill's impressive foot speed — he was a center for a Delaware state title-winning basketball team — and recovery time. So Vikings coaches want O'Neill to spend a lot of time with the squat rack, which remains a work in progress, according to coach Mike Zimmer.

"We're always trying to push that number up a little bit," O'Neill said of his 301 pounds. "It's not terribly hard, but it's something I have to be aware of and focus on every day."

A distant memory is O'Neill being a healthy scratch for last year's Week 1 victory over San Francisco. The sputtering start to his NFL career turned into a fine rookie season, during which O'Neill was one of a few offensive tackles not to allow a sack, according to Pro Football Focus, despite facing Chicago's Khalil Mack and New Orleans' Cameron Jordan.

"He really improved with the physicality and his demeanor," Zimmer said. "That really showed up toward the end of the year. He was much more physical and aggressive."

O'Neill credited one of the only Vikings players who can nearly see him eye to eye. Pro Bowl defensive end Danielle Hunter is his daily test in practice. Those one-on-one battles are some of the most compelling scenes in training camp.

When Hunter wins, O'Neill comes after him with questions.

"That's something I really like about him," Hunter said. "Not many times you'll see O-linemen ask a defensive end what they did wrong."

When Hunter bull-rushes through O'Neill, he comes back questioning why Hunter chose that move — not just how to defend it. So Hunter says O'Neill's hands were too far apart, exposing his chest. If O'Neill is beaten with an inside move, Hunter says he leaned on his outside foot. Should O'Neill square up perfectly, Hunter warns he'll grab and jerk him around to get him to stop his feet.

"You can tell he doesn't want to get beat how he normally gets beat," Hunter said. "He wants to get better, so he'll find a way."

O'Neill, who turns 24 next month, has found a sharpening stone in the Vikings' All-Pro pass rusher.

"Honestly, I can't say enough about how much he helps me and helped me last year," O'Neill said. "It's really, really good work and I'm really appreciative of it. He doesn't slow down, it's 1,000 miles per hour."

Off and running is how this Vikings offense envisions itself during the Sept. 8 opener against Atlanta.

A heavier and stronger O'Neill can help running back Dalvin Cook go a long way.

"We're running the ball a lot, which is a lot of fun," O'Neill said. "It's just fun to go after people, start running the ball, pound some beef."