If you are ever having one of those days or actually to avoid having one of those days, seek out nature, seek out to be just with yourself and the natural outdoors.
Go sit by the sea, or a river, walk in a park, sit on the bench and watch the world go by. Look up and seek out things we do not see often as we rarely look up from the pavement.
Be in the elements, the wind, the rain, cold, enjoy the vitamin D blast from the sun.
We as humans have only been urbanised for a tiny, tiny, tiny fraction of our history and we need all the well-being boost that nature gives. It totally re-energises us.
Connect with nature and ourselves.