When you take the waste out of your processes, you obtain flow. If you want a crash course on flow, I haven't ever found a better example than this improvement they made in a clinic to have the next patient prepared (the relevant example starts at 4:19, but I recommend the whole video for everyone with a heart in their chest; this is the way human beings are meant to work together, the way I see it.)
The critical point where a lot of waste is created, is in the process between one ill person leaving the doctor's and the next one coming in. But it's a narrow factor, upon which we can exert control. Let's have him ready, by the door. The rest of the people in the waiting room can go at their pace, no big deal. Simple, isn't it? Does your doctor do it? I can tell mine doesn't.
The mechanics under this simple example can be applied to any area in our lives. For example, for any item that you have to buy periodically, have the one you're using and one more waiting (that "next patient chair"). When you start to use that second one, that's the signal for you to replenish buying one more. You'll never run out of stuff.
In creative work, a way of translating this is leaving your stuff so that it is ready to go next time: do the preps and setups after the task, not before. Be kind to your future self so he can "come in" quickly.
I have a guitar and I'm gonna use it