This is one of the most important empirical "truth" I've heard, now from several prominent people in the field¹.
You are, in effect, prioritizing (self-)discipline over short-term performance, learning or productivity gains.
I would surmise that your bodymind² has in effect realized, learned, that compound effect is the best strategy for long-term results; and/or that systems are better than goals. The invariant requirement of any long-term strategy is enough discipline to execute it.
“Never, ever break promises to yourself.” is the real lesson to learn and never forget. The usual rationale goes like this:
Imagine two people, one who always does what they said they'll do, and another who never does what they said. How do you feel about the first one? Trustworthy? Reliable? Someone you can count on? Now what about the second? Empty-worded? Unreliable? Unworthy of trust? Lazy, big mouth, etc?
Now consider how "you" (the "it", your third eye observing yourself) is going to feel about "you" (the "I", the one who carries all the emotional weight) if you behave like person #2 above?
You need to be able to trust yourself. And this is based on facts, not words, just like how you judge anyone else.
That's why it's important, critical, to pause and ponder before making any promise to yourself: make sure you won't break it, make sure you'll be excellent with your own word. Be person #1, the reliable, the trustworthy, for yourself. Give yourself the facts to back that belief, because words, well, they're empty, and you're the only one who can't lie to you.
[1]: Off the top of my head, you hear it from Stephen Covey in the 7 habits (honesty with yourself), you heard it from Napoleon Hill and Dale Carnegie well before that, you heard it more recently from Brene Brown (in Daring Greatly and her TED talk on vulnerability and courage). Iirc, don't quote me on these, check twice, but the gist is correct.
[2]: Bodymind = body + mind (no duality), i.e. "all of you", your being, your brain and all the things that connect it to the real world including its own, your entire body