i just started working a very physically demanding job (construction) and i have no energy after getting off a 8hr shift of heavy lifting in the sun. I drink 2 gallons of water before even getting off. Before when i worked a desk job i had plenty left in me after work for a hard workout but now i need help finding a supplement i can take after work to scrape together some energy for the gym. is there anything i can take besides caffeine? i am not against it it is just that i take it all day at work to keep my head up. any suggestions would be well appreciated.