You can be 5 feet tall, built on a cat frame and still be dominant. Being dominant is much more about how you interact socially. And no, being the 'tough' guy doesn't help.

You can feel more confidant if you have some more muscle mass, but that's about it.

Now, about the testosterone. Exercise will make your testosterone go up for only a few minutes to an hour, which doesn't do much of a difference. (Same for sex btw; levels go up AFTER sex.) Besides, if you lack the hormone in any serious matters, you should seek a physician. Other than that, why would you want more? Because you think it's in direct proportion to your manliness?