But when I look a bit more closely, I have to admit it wasn't self-preservation that steered me away from all these habits but other quite random personal characteristics that aren't so impressive.
Eating too much makes me feel queasy and unwell. Drinking too much totally numbs my brain. Drugs might have claimed me if it wasn't for not knowing where to get them. And I could have been a couch potato if it wasn't for the physical restlessness that stops me sitting for very long.
Although we humans are supposed to have a strong self-preservation instinct, actually I think it's pretty feeble and often overwhelmed by our tendency to act on impulse regardless of the consequences. Especially when we just want to enjoy ourselves.
All the time I see people doing amazingly risky things, blatantly dicing with death and injury, oblivious to self-preservation. Motorists overtaking on blind bends, jaywalking pedestrians, drunks about to totter off station platforms, householders on wobbly ladders. They defy all the dangers, convinced they won't come to any harm. Or not even caring if they come to harm or not.
The honest truth is that often I'm as impulsive and reckless as the next person, and self-preservation is the last thing on my mind. If I've never come to any serious harm in my life, it's really more luck than judgment. I can stop feeling self-righteous because I'm not as canny as I think.
Another smug self-appraisal bites the dust.
