1. Working out regularly (3 times a week lifting weights), eating healthy, and playing team sports (co-ed soccer and volleyball). In my 30s, and still in the best shape I have ever been.

There was a time when I didn't work out regularly, and I have to say that a 'weak' body affects you in many way down the road. Trying to 'save time' by skipping working out, or not doing physical activities is counter productive. Similar to skipping sleep because you don't have time. It destroys your health in many ways.

2. Moving to the US as an exchange student (in high school), and living for a year with an american family that I had never met before.

3. Studying Computer Science