How come Dexter is always the fittest and strongest?

He never losses a one-on-one fight. He's always so strong and so fast and never run out of breath. Yet, you never see him workout or lift weights in all seasons. He's not on performance enhancement drugs. He never gets enough sleep and his diet isn't the best either. So how is he this strong!?

He never losses a one-on-one fight. He's always so strong and so fast and never run out of breath. Yet, you never see him workout or lift weights in all seasons. He's not on performance enhancement drugs. He never gets enough sleep and his diet isn't the best either. So how is he this strong!?