I feel better (mentally and physically) when I'm in shape and active. So I keep trying to feel the best, by being as healthy as possible, and fitness is a factor. (Cardio, strength, flexibility.) That's the primary reason. I also like how I look better when I'm active, so that's the secondary reason/bonus.
Same here, the mental and physical benefits are amazing! Being fit is essential for your body to destroy all of the toxins. If people only realized they feel so bad because of their diet and physical habits. Yes, looking good is a plus too!