In the former, you’re the opponent. Wrestling with your inner demons is fine, but demon fighting isn’t a great long-term strategy. The work will need to be finished no matter how many demons are left.
In the latter, you’re the companion. Believing that you’re capable is fine, so long as you do the work that you believe you’re capable of doing. Congratulating yourself for a job well done doesn’t make sense if you haven’t done anything.
My suggestion is a balance of the two. There will always be demons. And there will always be reasons to believe that you’re capable.