1. Failure (Academically)
  2. Break up (Specially with unworthy lovers or cheaters)
  3. Financial lows (They make you realise the value of philosophical piece of paper).
  4. Accidents (You realise value of free things like movement provided to us).
  5. Loss of loved ones forever.
  6. Loss of health

https://hemantpandeyblog.com/2017/09/23/what-should-be-the-most-important-thing-in-your-life/