Did you realize that when you complain you disallow your own well-being? In focusing upon what you don’t like or want to get rid of, you bring more energy to it and therefore attract more of the same to you.
This complaining doesn’t have to be about someone else or external circumstances, but simply your own well-being. Complaining about disease or your aching body takes you out of alignment with your highest or best self – and that DOES cause you pain. The further you venture from your best self, the more you will experience pain.
All this is not to ignore pain, but rather not turn extra attention toward it. What you resist persists and what you focus upon you create. Rather you might focus upon what you do want and how it would feel right in the present moment with a whole and healthy body. The same applies to everything else, your finances, golf game, business, relationships, etc.
Chronic attention to unwanted things holds you in a place of not being aligned to receive what you intend. Complaining disallows the solutions from reaching and positively affecting you. The same applies to maintaining what you already have. If you want to retain your healthy body, focus upon the experience of physical well-being.