Flattered by the amount of love my other post has received, thank you all!
To clarify though, the "hobbies and interests" should always be what YOU want. Some people love being healthy: long walks, 50 mile cycle rides, green tea etc. Some people love pints, wine, pizzas and a box of fags. There's no right or wrong, whatever floats your boat. I deliberately didn't cite "healthy living" in my earlier post as, let's be honest, despite the obvious benefits, it's not for everyone (least of all me!)
Where it tends to go wrong is when people try to go from one to the other without actually genuinely wanting to. From my experience, a decent amount of people can get away being "unhealthy", it's just that their lives are a few years shorter on average. But don't feel pressured into any particular way of living.
As long as you are comfortable with the fact that there may be some repercussions to booze, fags, drugs etc, then you can still be very happy. I've done funerals for 95 year old chain smokers and 60 year old teetotalers who walked 20 miles a day. Both of them were happy.