Most cancers are just bad luck, scream the headlines today, in typically irresponsible and ignorant fashion. The emphasis, of course, is on the entropic reality of genetics, and the implication is that you shouldn't care about the known bad things, because you might just be lucky (or unlucky) anyway.
This is bunk. It's stupid bunk, too, that preys on the human brain's aptitude for seeing patterns and reducing entropy.
We are all going to die*. We have very little control over what's going to kill us**. What we can control, if we survive long enough, is the extent to which life will suck as we get older. That suck includes, but is not limited to, cancers whose risks can be reduced, forms of diabetes, joint pain, difficulty walking, difficulty breathing and the sundry joys of an aging body.
Bad things happen. Bad things happen to good and bad people alike. Bad things happen anyway, no matter what. There is no way to prevent many bad things.
What you can do is reduce the risks of the bad things that you can prevent, and increase the odds of surviving the bad things you can't prevent. That's tricky, of course, because your mind's got to recognize the long term benefit to being healthier, and override the brain's desire for the shorter term benefit of spending less energy now.
You can choose not to get healthier, not to lose weight, not to stop smoking or whatever it is you're not doing, but for your own sake, and the sake of those around you, make a conscious choice. If you want to choose a miserable senescence or a terrible death, go for it. Don't kid yourself, however, that you're not choosing death when you are just taking the easy route.
At this time of year, resolutions abound. In a few weeks, resolve falters, and in a month or so, old habits prevail. Challenge yourself to choose to live longer, less painfully and more consciously, and when that resolve falters, remember why you made that resolution in the first place, and keep going.
** Excluding suicides.