I've grudgingly and gradually come to realize that, in the long term, a person's life is a lot more like an aircraft carrier than speedboat.
This is perhaps why short-term motivation can't get the job done. To turn an aircraft carrier, you need miles of room out at sea, plenty of fuel, plenty of timing, and you need to coordinate with very many staff people on the ship and any pilots up in the air.
"I want to do better writing" -- this wish is almost always answered for me, but not promptly. It's like I've put in an order to an Amazon.com of Creativity and Achievement, but chose the slow free Super Saver Shipping.
Sure enough, a week or two later, my writing will start improving. Better ideas will come; perhaps my subconscious was working them for the entire 7-14 days, beginning very subtle movements and firing of engines and re-doing schedules so that the aircraft carrier can imperceptibly begin turning.
But I notice that, when I'm rapidly changing objectives and not seeing things through to completion, it's like I'm missing the deliveries as they come; I'm out-running my own resources; I'm running faster than things can be achieved.
As you can imagine, this both exhausting and counterproductive.
"I want to do better writing" is something to commit to for a cycle, to commit to doing for at least a few months, or a half-year, or an entire year.
You can eventually cycle off of it, or put it on autopilot, of course. But "I want to do better writing today, then tomorrow is meh I'll do something else, and three days later I'll think about it again, and then not..."
This is tremendously wasteful. The aircraft carrier has no space and goes nowhere.
I've been scoping down, working very slowly, completing things one at a time. It occasionally feels stultifying and I still have the temptation during boring times to spin up some new brilliant creative thing.
But, no, that's not the way. I have a limited problemset of things I want to achieve right now that I'm working on, and it's amazing how I'll seem to stumble on near-magical "gifts" from the ether in these areas. But then, I think about it and review my journals, and no, it's not magical. It's an order I put in for that achievement a few weeks ago, and now it's arrived, and I'm still at the right address to claim it.