You can only split your energy so many ways before you become ineffective or only marginally effective at your goals. You're only human, you only have so much in the tank. As a husband/father I can only put about 2-3 things on my plate outside work/family. Working out, one side project/practice, maybe something else small. It took me a long time to stop fighting myself on this, but I feel like the reduction in stress has already paid off whatever I feel I've lost by missing out on this, that, or the other thing. If I want to fit something else in, I deliberately drop something else cold for a while--I don't balance them all.

Agree with what others have said about deadlines, I use that in tandem with the recognition about limited energy above. If I have tough hill to climb...nasty bug, difficult thing to write...I'll deliberately lay back and do really light work for the first part of the day, but I'll tell myself from 2 til quitting time or whatever I feel I can muster, I'm going to go all out. And then at quitting time, I quit. I find that I operate way more effectively this way than making myself "live" with a pain in the ass task from the beginning of the day to the end (or the end of it). Sometimes it won't take long in reality, but I could end up fighting it all day, and I find being motivated for a brief "charge" puts me in a much more effective frame of mind.