Just think about the possibilities that he might have.

Poker players tend to have one of two problems:
1) They're too passive. They become calling stations that are always afraid of things and lose value forever.
2) They're too aggressive, seeking out anything and everything to attack. They get trapped and will not believe their instincts when it is clear that they are behind.

You're #2. I'd suggest trying to think about what your opponent may have and assign probabilities to each hand that you think he might have. Then, do a simple Expected Value calculation in your head and take it from there.

Sometimes it's good to get caught up in the heat of the battle, but for us aggressive players (I'm a #2 type as well), we have to pick our battles wisely.