Think of all the other things....

....you could be doing, and all the other places you could be. Think about the other choices you might have made and the options that these, in turn, might have given rise to. Then, when you have really given yourself a king-size headache, stop thinking such thoughts. You are doing what you are doing for a reason. The 'what-ifs' are all irrelevant.

But if you continue to pay attention to them, they will sap vital energy and prevent you from making the most of 'what is.'

Mix a little foolishness with your serious plans.  It is lovely to be silly at the right moment.   (Horace)