What was the biggest crisis of your life and what have you learnt from that incident?

Hit by depression, being idle for 8 years, broken. I learned to enjoy small things in life and that life is a chain of changes. Today you're successful, tomorrow you may be out of the market, but like an elevator, life goes up and down. When you understand this (read about Stoicism) then you can be ready for the changes coming - they'll come for sure.