Theres quite clear evidence its not a health risk, quite to the contrary, it can offer a number of positive health benefits (wikipedia has a decent summary of some of the studies). I've been a vegetarian for around 11 years now and i run and lift weights, its never impacted upon me.
Your body is obviously adaptable, its not as rigid as people might think. If you're low in iron, your body increases the production of a protein that soaks up iron for example.
Theres obvious health benefits in eating less red meat, same with a vegetarian diet overall.
As for finding food, i usually have no problem at all. Pretty much every eating establishment in Australia usually has at least one vegetarian item. In other countries it might be a lot harder but here i've been fine.