Wait till you have a serious accident or 'near death' experience..
I had a smash on my motorbike many years back - a drunken civilian who worked for the police drove into me. I spent almost 2 years unable to walk, not knowing if I would keep both legs or just have one, and had countless operations - I am currently off work having had yet another op, 23 years on to fuse my ankle.
Now this smash made me stop. I lost my house, my business and my team of guys I employed. However, I was nursed by the woman who is now my wife, and mother to my kids.
I stopped wasting time, stopped living it large, getting smashed and being crazy, though I still enjoy myself plenty. Suddenly, life became precious, valuable and a major source of pleasure. Not to say i don't get down - being unable to walk due to pain for the last 18 months before my last op was really tough, being unable to walk properly now is also a bummer (I am a builder, so need to be fairly mobile) and I am now waiting to have another op on my other foot in a few months (another 3 months on crutches to enjoy..)
I know plenty of people who have had it much worse than me, but in some ways those who suffer seem to find more pleasure in the everyday stuff - if not for my kids I would have topped myself a few years back, but there is so much to enjoy, and it can all disappear so easily, so grab it, spend what you don't have, try anything a few times and be sure to treat other people well, as they deserve it !