We may not realise it but there is structure to our existence, this I have come to believe in the course of a long life.
Just as plants and animals evolve physically to a higher form, so we evolve to a higher form in terms of our character or essential self. Some say this evolution takes several lifetimes, we have passed this way before, we will pass this way again.
To learn the lessons that lead to the evolution of our spirit or essential self we have free will. Nothing is pre-determined, nothing is destined to be, it's up to us to make what we will of our lives.
Unfortunately, wisdom is often gained through suffering. That which does not destroy us makes us stronger and all that. Not for ever by still waters. So some folk encounter high anxiety and depression to cope with: we can deal with it because we have free will. No use blaming luck, fate or the Master of the Universe.
In time we overcome our high anxiety and depression or learn to control it. Life is not a fixed fate.
We are free to do what we will, thus with the inevitability of gradualness we evolve to a higher form.