The way I see it, it's quite possible to get "stuck" in a circle of excuses: "I can't do A because of B, and I can't do anything about B because of C..." There's a cute little folk song about this; you might already know it. I'd love to post a link to it if I could, but anyone can find it easily by Googling on the phrase (quotes and all), "there's a hole in the bucket".

The quickest way I've found to stop wondering if I'm using something as an excuse, is not to bother with excuses at all. For example (without getting into how often, or not, I read the Bible): when I don't read the Bible it's not because I'm depressed; it's because I don't read the Bible.

That's a lot like the way you put it but (IMO) invites even fewer followup questions from nagging daughters and such:

... I'm not doing Bible reading right now because I'm making other choices.