It used to bother him that his team, the New England Revolution, couldn't win the big one - 0 for 3 in Major League Soccer Cup title games - as it heads into another "big one" this Sunday in Washington, D.C.
It used to bother him that the U.S. National team twice has cut him from the final roster for the World Cup team, despite everyone knowing he was the best goal scorer with American blood running through his veins.
But Twellman says it all changed on a family trip to Hawaii after last season.
"It was the hardest year of my life," said the 27-year-old Twellman. "I got cut from the national team (in '06), which was tough. Then three days later my grandfather (ex-major leaguer Jim Delsing) dies. There was a lot going on that was tough to deal with.
"Then we went on a family trip to Hawaii and it was there I said I was sick of being miserable. I was going to enjoy my life."
The All-American smile and good looks are hard to miss. So is his hunger.
Twellman's team is playing in its third straight MLS Cup game and fourth in six years.
If he's not the Revs' version of Tom Brady or David Ortiz, he's close.
Twellman scored his 100th goal of his MLS career (176 games including playoffs) in last Saturday's semifinal, a 1-0 win over the Chicago Fire.
It's easily the most goals for any MLS player over that span. His 91 regular-season goals are 10 better than Dallas sensation Carlos Ruiz's 81.
But it was his last goal, sending the Revs to this weekend's title game, that was maybe the best of his career - the bicycle kick.
Thirty years ago, the great Pele made the bicycle kick his highlight play while playing for the New York Cosmos of the North American Soccer League.
To put it in perspective for non-soccer fans, it's like a Little Leaguer dreaming of hitting a grand slam on a 3-and-2 pitch with two outs in the bottom of the ninth.
Covered by two Chicago Fire defenders about 20 feet in front of the goal, the ball was kicked from the sidelines toward Twellman. A Chicago defender headed the ball, which went straight up in the air.