How do I increase my endurance? I've been running three miles, three times a week, for about six months. I can't seem to run more than three miles at a time. Do you have any tips for building endurance?
When lifting weights, do I need to work certain sets of muscles in tandem? For instance, if I work out my back, should I work out my chest muscles, too, so that one doesn't get overdeveloped and affect my posture?
I'm 56 and beginning to feel old. When I get up in the morning, my lower back is stiff, making it hard to put on socks. My back loosens up in the next hour or so of movement. Is there an exercise that would help me avoid that early morning discomfort?