Intention. I try to remind myself why I am doing what I am doing and why X or Y should be done.

If the end result is really important to me, I will find time to do it. Because the alternative is, not reaching that goal that is important for me.

There are also things that are more important than others and connected to deadlines, so I try to do them in that order.

However, sometimes, immediacy is a stronger driver. If I feel like doing X over Y and the situation/surroundings allow for X better than Y, then I will do X. While it might be less important than Y in the big picture, it is one thing ticked off my list, getting me closed to Y (because, less distraction).

I can relate to what flagamuffin said, somehow. During my studies, I worked in a variety of labs, with absolutely different research contexts. While the subjects, methods and the questioning was different, there were things that I learned about Zebrafish that I was able to use in apoptosis in cancer cells and later on in axon regeneration etc.

What I am trying to say is, in retrospect, nothing I ever did feels like a waste of time. Not the 6 years I spent playing MMORPGs (learned english, met wonderful people) or all the mistakes or failed attempts I did. Somehow, you always learn something.