So when I find myself procrastinating I quickly decide: I'm not going to do it at all. If deciding that gives me sense of relief then I take it was a sign I was right to drop it.
But if decding that feels wrong then I will contemplate on it, because maybe it was pointing towards something that I should be looking into more closely.
For example, our culture is really trying to sell the idea of "I should be going to gym" but no, I shouldn't. Instead it's probably a good idea to put my muscles into work somehow but then that doesn't have to be gym.
But I can tell that everytime I'm doing the thing that's good for me: I'm in flow and things are rolling forward very nicely. I don't need anyone telling me what I should or should not.