| lol, at 6 feet and 146 pounds, that's pretty damn skinny. It's not about BMI, it's about muscle mass compared to body fat.
If BMI truly ruled the world, every "healthy" person would be skinny as a twig with relatively high bodyfat compared to muscle mass.
But if you really want to maximize your potential, get plenty of rest, take up swimming long distances, eat all your green veggies, take your vitamins, drink milk, and cross your fingers. | 
