There’s a famous question, why do we daven if Hashem knows what’s best for us?

Reb Yosef Albo explains that Teffilah is not to change Hashem’s mind but rather it changes us, making us into a new vessel to get blessings that we couldn’t have gotten before…

I’d like to add…

Why indeed DOES prayer change us?

When we daven, we automatically strengthen our feeling of dependence on Hashem which creates a "relationship", and that's what Hashem really wants.

So for example, we daven and tell Hashem, "I am sick now and I know that I can't heal myself. And I know that you want me to FEEL how much I need You so we can have a closer relationship.

Only You Hashem, can heal me. Doctors are only your messengers, and even medicines can only work if you want them to.

When I ask you to heal me Hashem, I am not trying to change your decree, because You know far better than me what's good for me. Rather I am declaring my full trust that You are the only one with the power to heal me, should You so desire."

By doing this, we strengthen our Emunah and relationship with Hashem, which automatically makes us a different person with different vessels for His blessing.