Many years ago I was working a construction project on a flourmill. From one of the upper windows I watched a man on the dock stacking bags of flour as they came off a conveyor. He had a rhythm that was in time with the moving bags and merely had to guide them onto the waiting pallet.
Once in awhile he would get just a bit behind, forcing him to struggle with the next bag. Of course this made him even later to catch the bag after that and so on. When this happened, he just let a bag go by and got back in sync with the conveyor.
Life is like that constant flow of bags, sometimes it comes at us faster than we can reasonably handle. One of the secrets of a stress free and productive life is knowing when to let a bag go by.