RICHMOND, Va. - Something’s always eating at Gilbert Arenas.

Real or perceived, tangible or not, slights lurk around every corner for the Washington Wizards’ All-Star guard. No matter his accolades, Arenas seems to seek, gather and, yes, cherish affronts, precisely the way he collects autographed NBA jerseys — and he owns hundreds of those, from all sorts of players and eras.

Stop him for a few questions after a training camp practice, and out slides a mention of how that very morning he was reading one person’s preseason ranking of top NBA players and was shocked — shocked! — to find himself down at No. 20.

“Duncan’s No. 1, Kobe’s No. 2. Then they’ve got all them bums in front of me,” Arenas said this week, a can-you-believe-it? tone in his voice and mischief in his eyes. “I’m 20; I feel I’m in the top five. There’s motivation right there.”

Typical Gil, Wizards coach Eddie Jordan or teammates might say, and they might even laugh or roll their eyes. What they — and fans — are not as accustomed to is Arenas’ questioning himself, being the very source of the sort of underestimation that drives the guy.

Yet that is precisely what Arenas did in the weeks right after last season ended prematurely, after he tore up his left knee during a game in April. What he did as he began the arduous workouts needed to return from surgery. What he did knowing full well how crucial that knee is to what he does and what he loves.

“I was doubting myself early,” Arenas acknowledged during a chat with a small group of reporters last week in Washington. “When you’re sitting there, hurting, you can’t move, and you just start looking down at your knee, and you’re walking and trying to run, and you’re limping, you’re like, ’This is how it’s going to be?’ ...

“Then I was like, ’I’m going to wait until December before I can kick it into gear?”’ he continued. “So I just started pushing myself — harder and harder and harder and harder.”

Seven days a week, five to eight hours a day and sometimes more, throughout the dog days of summer. Even though Wizards strength and conditioning coach Drew Cleary already considered him “a workaholic,” Arenas knew he needed to push, needed to do more than ever.

Why?

To add to his three All-Star selections?

To average 28.4 points like he did in 2006-07 or 29.3 like in 2005-06?

To be able to call 50-point games and deliver?

To lengthen his highlight reel of walk-away-’cause-you-know-it’s-goin’-in buzzer beaters?

To increase his array of aliases (“Hibachi,” “Agent Zero,” etc.)?

To land more sneaker commercials or more video game covers?

To assure himself of getting the maximum money from the Wizards when he opts out of his contract at the end of the upcoming season?

No. Not necessarily.

Why then?

To win more games when it truly counts, to finally get beyond the second round of the playoffs — because, as he put it last week, anything less for Arenas and the Wizards this season will be “a failure.”

“The chip for Gilbert is: Is he one of those players? Is he a LeBron James? Can he take his team to the finals?” team captain Antawn Jamison said. “Can he win a championship like D-Wade and, you know, Tim Duncan?”

Which is why Arenas would strap a 15-pound weight to his left ankle and dangle the leg off the edge of his bed, forcing his knee to extend. “That,” he said, “was pain.”

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Why he would run the 1,392 steps along one of the seating levels above the team’s home court, up and down, up and down, up and down, hoping with each stair to grind some of the stiffness from his knee and some of the worry from his mind.

“I’ve got to prove myself coming back from this injury,” Arenas said last week.

“I’ve got to prove myself that I’m an MVP candidate in this league, and I’m one of the best point guards in this league. So I’m going to come back with that same passion, that same fire. If I have to go out there and score 70 or 80, it’s going to happen, but I don’t shoot for those goals. Goals of mine are always about winning the game.”

Which is why he would ride his bicycle through Washington for an hour or so at a time, three days a week, forcing his knee to keep churning. Lest anyone forget this is Gilbert Arenas, he was sure to explain that he never wore a helmet because he didn’t want to “look goofy” and stayed on the sidewalks not streets because, “There’s cars on the street. I’d rather hit a person than a car, any day.”

Why he would trek to a D.C. public high school and first spend time on the track — four 100-meter sprints, four 200s, three 300s, and two 400s — then chug away on the litter-specked football field with a pair of red-and-blue parachutes strapped to his waist for resistance.

“When I first started running, I was favoring it,” Arenas said, recalling that a teammate who joined him for track work noticed a limp. “We just kept running and running and running, just trying to run it out.”

Why he would do drills on the court that involved dribbling a basketball past Cleary, who tried to knock Arenas off stride by pounding on him with a foam pad that looked like something NFL linemen would use in practice.

And, of course, why Arenas would shoot. Boy, did he shoot, sometimes for 2½ hours straight. At one point, Arenas said, his goal was to reach 100,000 made baskets by a certain date, and he was way ahead of pace — but then his shoulders started feeling stiff and, well, suddenly, it didn’t seem like such a good idea.