You’re already too busy. Either your primary career demands more than the old standard 40 hours (how long ago was that!) or your so-called freelance life leaves you free to work 24-7. Or you’re out of work and the ennui is killing you.

Get a side gig! A side gig is something you’ve always wanted to do, or a brilliant business idea you’ve had but never tried out, or something you think might make money and be fun, too. Maybe it’s producing a food product, or writing articles, or dog training, or some craft product, or consulting. Here are 10 reasons why:

1. It stretches your brain. Even if you’re a busy, successful professional you can get stale by only concentrating on one thing. A side gig potentially introduces you to a whole different group of people, ideas, and ways of looking at the world, and gives you an opportunity for cross fertilization.
2. It gives you new contacts. Instead of the same old colleagues doing the same old things, you can meet people from worlds you never encounter in your main job, and perhaps friends you never would have met in your primary circle. When people are unhappy in retirement, one of the reasons why is that they lose their “friends” along with their job. A side gig can widen your circle of friends, and they won’t all be based on shop talk.
3. The extra money can be important. A good side gig makes at least $500-$1,000 per month. For some, that can be the difference between the basics and the luxuries; for others, it’s chump change or, better, fun money. But for most people, saving an extra $1,000 per month wouldn’t be a bad thing for either their emergency fund or their retirement. Even if you don’t need the money, setting a goal to actually make money forces you to test your great idea or refine it, all good. Or just give it away—I can think of one or two charities that would welcome a $12,000 yearly donation.
4. You can laugh a little more at the boss. You know you have at least a little money coming in on the side.
5. It gives you something else, hopefully fun, to think about. Even if you are the boss.
6. You can employ your kids. This has the benefit of transferring cash for college to them in a potentially tax advantaged way, as well as teaching them a lot about entrepreneurship, another good thing.
7. It can be very successful. More than one side gig has morphed into at least as good or better business than the main one. Think Paul Newman or Scott Turow.
8. It can tide you over in an emergency. It’s a lot easier to cope with a job change or loss if you have a little coming in on the side, and something else to think about.
9. You can test a new business on the side, with far less risk than quitting and starting from scratch. Similarly, you can dump a bum idea and try another one. You’re less likely to waste time and effort, and even if it’s a bust, you haven’t invested everything in it.
10. It’s an excellent retirement plan. If you pick a side gig that doesn’t require a great deal of physical labor, it can go on as long as you wish, and promote your engagement with the world—you’ll have to keep your “edge”. Also, it can be financially significant in retirement. To generate a $12,000 per year withdrawal from investments, you need an extra $300,000 in principal.

Obviously, I’m not talking about bagging at the grocery store or delivering pizza, although I admire people who make those efforts, too. Go out and create something new and useful—we’ll all be better for it.