Sustaining motivation

I am having a hard time sustaining motivation toward any one goal. I get bored or there is something else that seems more interesting, pressing etc.
I can’t pinpoint my thoughts exactly, but here are a few that tend to be part of my downloads:
It’s not worth it
Life’s too short
It won’t matter anyway
Why bother
I’ve tried so many times and haven’t been successful, it will be the same this time
I don’t have what it takes

These are in relation to eating or drinking off protocol or even creating a protocol.

I’m struggling and can’t find any better believable thoughts.