LOS ANGELES | David Walton has been at television’s starting gate so often he’s not quite sure how to run the race.

“I used to be pessimistic just to protect myself,” he says. “Now I go all in. It’s an awful, gut-wrenching feeling to have something you love go away but you get through it. And then you get good at going through it.”

In the last decade, Walton has starred in six series, none with more than two years to its credit. Now, he’s in “About a Boy” and, yup, he thinks it’s the one.

“It’s the thoroughbred. It feels like Secretariat,” he says. “It has the best showrunner in town (‘Friday Night Lights’ producer Jason Katims), the pilot is very strong and the subject matter has a lot of appeal.”

Based on the Hugh Grant film, TV’s “About a Boy” stars Walton as a single, unemployed musician who takes a neighbor kid under wing and tries to teach him the realities of life – something he’s not getting from his single, sometimes needy mom.

“It has a simple premise, which is hard to get on the air because they don’t sell. But those are the best shows,” Walton says. In 30 minutes, his “About a Boy” covers as much territory as Grant’s did in two hours – a good sign.

But, as the actor knows, that first outing is crucial.

“I thought ‘Perfect Couples’ (his 2010 series) could go on forever because we had the six best up-and-comers in the business. We had great writers. But it didn’t get the ratings. ‘Perfect Couples’ was better than its pilot…but nobody got to see what it was going to be.”

“Bent” (his 2012 entry) “was dead on arrival because the series was too weak. It was a good show but it didn’t have a chance.”

Run through the others – “Quarterlife” (2008), “Heist” (2006), “The Loop” (2006) and “Cracking Up” (2004) – and a pattern emerges. In most, Walton has played the guy who suffers from arrested development.

“It was so insulting that I kept getting these roles that I went out and had two kids with my wife,” he says with a laugh.

In truth, the 35-year-old Boston native is hardly the guy least likely. He got a degree in psychology from Brown University, studied drama in London and had incredibly supportive parents.

When he told them he wanted to be an actor, they never tried to dissuade him. “It’s one thing to be clapping for your boy when he’s 12 years old. It’s another thing to be like, ‘You want to make money doing this?’ Now that I’m a parent, I can’t believe they didn’t say more. I will actively be saying, ‘You are not doing acting until you are fully a free person at age 18.’”

The career choice, though, has been a good one. “I wasn’t a slacker. I was always very ambitious about my acting career.”

And he’s a pretty good citizen of the world, too. Walton is a Big Brother in the Big Brothers Big Sisters program. He knows the world of “About a Boy.”

“I always say, ‘find something – whatever it is – that carbonates you. Make a list and whatever’s at the top, go, dive in. I did a freshman play at my high school and that was it. I was hooked.”

Now, Walton is placing his bets on “About a Boy,” a series that feels just right. He and Benjamin Stockham, who plays his impressionable neighbor, have the same outlook on life.

“We’re good at teasing each other. That’s our dynamic,” Walton says.

When the two had to eat ribs for a scene, they quickly discovered the value of a spit bucket. “If you didn’t, you’d be puking the rest of the day.”

Unlike the film version of “About a Boy” – which Walton didn’t see – the TV edition features a much more complex adult male. “It makes you realize what can churn underneath all that – something that Katims is so good at.”

Now, of course, the series’ fate is in the viewers’ hands. If it succeeds, Walton figures he can fuel a personal dream – creating films, show with friends who are also in the business. If it doesn’t, he’s back at that starting gate.

“A series is this juggernaut,” he explains. “You have millions of dollars invested and it’s like a rocket ship. The engine starts, it goes on the air and it either soars or it crashes. It’s an exciting, but nervous, time.”