A stagnant pool is stagnant because it’s cut off from everything. It hasn’t been replenished from its past, and it has nowhere to go. The people who suffer from despair suffer a similar fate. They haven’t gotten the experience from their past to see a clear way forward. It’s for that reason that everyone should be taught problem-solving techniques as soon as possible so that they will never drown in despair.
Problem-solving
There’s one premise about problem-solving that everyone should agree on, and that is, there’s always a way forward. If you don’t know the way, someone else will point you in the right direction as long as you’re brave enough to ask the question. However, you may not like their answer, but the path of least resistance rarely takes you to your desired destination unless you’re incredibly lucky.
There will be problems where finding the right answer will take time. During those times, you need to take into consideration the following quote.

It’s not the end of the world, and should it ever come to pass, worrying about it will be futile.
P.S. Diving into despair is never going to be the right answer to any problem.