Not having some idea of which direction you want to start out in is not a good thing because the alternative is just "sitting". And one can't sit still, one is either going toward something or getting further away from anything. The less you do, the harder it is to do anything. Everything takes "practice" (including setting goals and working on them) and if you aren't doing anything at all, there will come a day when you literally "can't" because the effort required will be beyond you.

It's like I'm faced with now; I'm 61 and my muscles are atrophying and unless I work with that, I'll be sitting/bed ridden sooner rather than later?

http://news.bbc.co.uk/2/hi/health/4502862.stm

The difficulties one faces, one has to keep working on/with, not to "cure" them necessarily but just to slow them so you get the maximum benefit of the time you have. No, I'm not going to join "Biggest Loser" and exercise 5 hours a day the rest of my life because my payback, at this stage, would not make that worth it, even if it were something I really enjoyed doing (which I do not :-) But you are young so your payback for "doing" is much greater now than it will be in the future.