This quote, by Joseph Campbell, talks about being willing to let go of the life you planned. This is not to say you give up easily when things don’t go according to plan or you don’t plan things out at all. There’s nothing wrong with persevering or planning your future to a T. Being able to do that is a good thing that typically sets you up for success.
However, understand that sometimes things don’t work out because they aren’t meant to. They were only meant to teach you a life lesson. But the more you fixate on them, the less likely you are to see or accept any alternative, including an alternative that might actually be the path you’re meant to take.
So continue to plan out your life. Meanwhile, know when it’s time to let go and then be willing to let go. Who knows what else awaits when one door keeps closing.