MS application is stressing me out

I know I'm not the only one; most, if not all, probably stress out when it comes to applications. I'm usually very chill, but throughout my application process (I'm currently applying to one university this year; I might apply to more next year), some days I feel optimistic, some days I feel like it wouldn't matter much if I don't get admitted—at least I tried—and some days I feel so bad thinking what if I don't make it. I've been fortunate enough to have a prospective advisor who is very responsive to my emails, has given me readings, initiated an online meeting, and has offered to check my proposal and reimburse my application fee as well.

I just can't help feeling anxious about it. Currently, I'm trying to polish my research proposal, and I can't help but worry that it's not good enough.

Anyway, to those who are in the midst of applications or have already submitted, good luck!