. . . programming requires more concentration than other activities. It's the reason programmers get upset about 'quick interruptions' - such interruptions are tantamount to asking a juggler to keep three balls in the air and hold your groceries at the same time.
Let go of what has passed. Let go of what may come. Let go of what is happening now. Don't try to figure anything out. Don't try to make anything happen. Relax, right now, and rest.