I know this is really late in reply… This is cheap & easy… Take a couple of Vitamin B complex vitamins. They make your blood carry more O2, so you feel less tired. But, for a caveat, take them at night – before you go to bed, since they will also make you hungry (and they will make your pee turn neon yellow ). Any extra Vit B you get will be excretes, since it is a water soluble vitamin. You can get the Vit B for your local dollar or 99? store.