Video games. I used to play 4-6 hours per day (or often more), every day. It was kind of my default activity when I wasn't forced to do something else. If I ran out of steam trying to focus on work or family I would drift into playing a video game. The result was a MASSIVE sink of time into something that left me with little afterwards. I didn't learn new things, I drifted away from my kids, and I didn't take care of my home.

Video games are fine. They're entertaining, but they're also potentially life consuming. I watch people who want to do more with their lives, but instead they just put more time into some game or another.

I managed to kick the habit and it's been a great 10 years since then where I play very little and only in very short, controlled bursts when I can play with my kids for a bit (they usually destroy me these days). With all of that saved time, my career started flying, my home is in better shape, and I actually don't drift away from family events like I used to.