Are people more intent on fitness for personal health or to impress others?

Depends on the individual.

Many like myself begin it initially to impress others, but soon learn that it stems much deeper than just trying to impress others.

It is not just the asthetics.

It's the whole life style. It's the pride, the discipline, the challenge, and the reward of smashing personal bests. It's builds confidence, it directly improve happiness. It reminds you, that you're still alive.

It's not about you vs everyone else. It's about you, vs yourself. You do what others Arnt, you train better, you do what others won't, so tomorrow you will do what they cannot.

Your body is an amazingly powerful machine, respect it.

Judging from the answers here on YA, I would say that the majority of the younger folks seem to be in it for the looks. Many juicy young men wanting to know how to get "big arms" and nothing about the rest of their body... And young girls wanting silly things like "thigh gaps" and worried about getting "muscly" legs....

Older questioners seem to be more concerned with health.

I don't really care about how I look. I don't really care about my health. I don't really care what any one thinks about what I do. I do what I do because ammonia caps, chalk and bloody shins are far preferable to the other ways of dealing with life.