Have you though of HRT kwaddilove? It can help lift you out of lethargy! Otherwise diet and exercise are good things to focus on - to make sure you arse getting good balance of nutrients, some supplements if you have a digestive condition that means you don't absorb nutrients from food, lots of fruit and veg, keeping active. Being physically tired and then getting enough rest can help raise energy levels overall! Sorry if I'm preaching to converted!
Hurdity x