system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How come being sad makes me choose to partake in unhealthy lifestyles?

For the most part I try to be a healthy person. I do some moderate exercise regularly, try not to be sedentary for too long without getting up and moving around, and I watch what I eat. But once I get sad or depressed for various reasons, all I'll want to do is sit at my computer all day eating junkfood. Why does being sad cause me to want to be unhealthy?
gpt
Those unhealthy things are easy to go to because they offer immediate gratification. You don't get the same instant reward from running on a treadmill for an hour than you do eating a bag of Doritos (despite the fact that you'll probably feel better if you do the former regularly instead of the latter) . When you're sad, you're looking for ways to fix that negative emotion, so naturally you gravitate towards things that will fix it quickly. The problem is just that most of those things are bad for you in the long run, and the things that are good for you in the long run aren't usually immediately gratifying.