2015 was, for me, mostly just an extension of 2014 in this regard, as I had a big "life altering" experience late in 2014. I had a heart-attack in November 2014 and could well have died. Luckily I live close to a good ER and what-not and got prompt treatment and I'm mostly fine now. I'm on a bunch of new medicines, but otherwise things are mostly back to normal. I did some mountain bike racing this summer, before I tore my rotator cuff in a fall and switched to mostly road cycling until I get my shoulder fixed up.

Soo... to answer the question... and hopefully without sound to glib, I'd say "take your health seriously. Stuff creeps up on you". That is, all the warnings you hear about "eat right, exercise, keep your cholesterol down", etc... yeah, that stuff does matter. And yes, it can happen to you. I know, because I was one more person walking around thinking "that stuff only happens to other people" until I was on the back of an ambulance wondering if I was going to die.

I really don't like being the preachy type, but if I have any useful advice to share, I'd say it's this... invest in taking care of your body. And by "invest" I mean, time, knowledge, money, exercise, food, whatever elements you need to leverage to maximize your health. Read a book like Cholesterol Clarity and understand how this cholesterol stuff really works. If you're a little overweight (or a lot) find a way to start getting more exercise. Buy a bicycle, or a skateboard, or a surfboard, or just some comfortable walking shoes, whatever. Throw out the Doritos and sugary sodas and shit. Learn to eat healthy. Quit smoking if you smoke. That sort of thing.