The most important lesson that life has taught me, is:
"You must take care of your body. mind, and soul above all else."
For the longest time I abused all three of these, in just about every way possible.
I learned a few things during this time, but the most important thing I learned, is that without caring for yourself first and foremost, you will lack in virtually every aspect of life.
You will be of little use to others if you do not make sure your own needs are fulfilled properly, and that your mental health is suitable for interacting with others.
Maintaining proper diet and exercise first and foremost will give you a good foundation to maintain positive mind and soul. Caring for your mind and soul in a productive manner will help you to fulfill your purpose, as well as the energy you exude onto others, will become more positive and magnetic.
I hope this answer was helpful.