You have things you want to do, but probably not enough time or energy. You can only do one thing at a time (multitasking is a lie), and switching between projects eats time and energy for lunch.
Done is better than perfect
One reason I don't get as much done as I'd like is perfectionism. I have an idea of the ideal outcome, and I can't ship until I hit that unrealistic target.
So I work and work, and work, then get bored or distracted, and nothing gets finished.
How, then, can I create more output and ship a higher quality output?
Make a lot of pots
I remember a story I heard about a pottery class. The teacher decided to run an experiment. Half of the students were to spend the next two weeks creating the best pot they could. The other half, to make as many pots as they could.
At the end of the two weeks, the best pots created were from the second group. Because they made many pots, they iterated, experimented, and drastically improved the quality of their work.
How to ship more
It turns out there are three things you should focus on reducing if you want to ship more, and through iteration, achieve higher quality output over time.
How can you make it easier? Deciding to ship when something is "good enough" can reduce a whole lot of resistance. Understand that even if something seems somewhat shitty, you'll get better faster by shipping more things that are good enough.
Can you ship something simpler? Breaking a big project into smaller, simpler deliverables can make it easier to finish. Instead of coordinating many complicated interactions in your head, reduce the complexity until it's manageable.
Don't start tomorrow or next week, or when you think you're "ready" to go. Just start now. The longer you wait to work on a project, the more likely you're going to lose whatever motivation and inertia you have right now. It would be best if you also tried to work in big chunks of time. If you block off 3+ hours, you're more likely to get into a flow state, which will help you produce more in less time.