How do I work out everyday and not feel depleted?

I used to ride the upright bike 3-4 times a week, now I'm doing it pretty much everyday. After about a week of this new regimen, I've begun to feel depleted most days and don't feel like I can eat or drink enough to revive myself. I mainly work out for the good feeling it gives me for the rest of the day but this depleted feeling is starting to outweigh any positive benefits. If possible, I'd like to still be able to ride the bike everyday and not take days off. I realize it's commonly a good idea to take days off from working out, but it's not like I'm doing intense strength training. I'm a healthy young guy; I feel like I should be able to hop on the upright bike once a day for a 30 minute ride. Is there anything special I can eat or drink after the workout to get me back on track and allow me to workout everyday? Maybe a protein shake? I try to eat well already (including things high in protein) and would rather not have to overhaul my entire diet and with specialized food.