Rubik
Cubing is a very rewarding hobby which also fills a lot of gaps in your daily life. It is great if you have kids, as you are likely to spend time sitting on a bench at a park. It also works great for relieving stress since it has a large component of fidgeting.
Did you know that most people can solve their first cube within 2 hours by just following a manual? After that, if you get hooked, it is an endless spiral.
You can try to beat your best times, solve it one-handed, blindfolded, learn party tricks, solve larger cubes with more pieces, and so on … You can do most of the practice by just spinning your cube along your day without dedicating explicit time to the hobby. Next thing you know is that you carry a cube everywhere with you.
My most recent achievement is to solve Rubik’s cube blindfolded using Old Pochmann’s mehtod.
I am still practicing blindfolded solves, and I can consistently solve it 2 out of 3 times. After you memorize the cube and put the blindfold, it takes more than 500 moves to solve it. So it is really easy to mess it up.
Here is a video of my first blindfolded solve.