Better than you, riddle and security

1. I meet Pankaj in the gym who tells me he has been asked to lose 10 kgs. What are you doing here? Have you been asked to lose weight too? he asks... I smirk, and tell him (truthfully, by the way), that I'm not overweight. I'm here to tone myself up and lose the lethargy. Evil laughter (mine) follows.
2. Why is it that after a workout in the gym I actually feel more energetic rather than exhausted?
3. A friend (identity concealed to protect privacy) emails to say that she's in an anti-social, shun-all-human-contact mode currently. She hastens to add that I needn't worry, I'd never fall in that category ever.