Sometimes - like today - I am not interested in anything. I just feel lethargic. I walk around, try to sleep, try to work, try to lift some weights... nothing works. I'm just bored. I play computer games and feel bad for wasting time that I could use to build my startup, do sports, plan a holiday or whatever. But I simply find no energy for any of these tasks. I know that in a day or two I will be full of energy again. Maybe even later on today. But these lethargic moments come often. Once every few days I guess. Any Ideas how to approach this kind of situation?