Relaxing. I just finished my 1 AM workout. I have to be really fucking strong. I'm only 5'0 at 15, and I look childish so I have to compensate. Also, I am playing bass drum in marching band next year, and I have slight scoliosis (curvature) in my spine, so I want to be strong and easy on my back. Even lifting weights causes numbness on my spine. I have a pinched nerve in my mid back I think.
As an afterthought, weightlifting increases the level of testosterone and growth hormone in one's body. Also, it increases endorphin levels and makes me more confident and I feel more brutal after I work out.