Water adapts to shape without becoming something else.

Water takes the shape of whatever holds it and remains completely itself. That is a different thing from being formless. It has properties that never change, and its flexibility about form is what lets it get everywhere and outlast almost everything it meets.

There is a distinction worth keeping: adapting your approach is not the same as abandoning what you are. Ask which of your rigidities are actually about identity and which are just about form. The second kind can be given up cheaply, and usually should be.