Vanity covers fitness - as when you're fit - you're looking good too. However categorising fitness in the vanity department can for those of us who aren't natural sportsmen give a great focus and motivation - doing exercise, not for enjoyment - but to gain so much.
The question is: What do you want to gain?
to look good, or youthful - both can add to your personal & professional life - by looking relevant and current.
My entire personal health & fitness regime - all that I do for me - is based around vanity and virility, as for me those are what I want - both - and in their broadest context - and as you can imagine vanity is a very broad aspect.
However at the age of 56 this task can get harder and harder - but then in the context of virility perhaps this is a good thing.