Drink Water!

That's right, drink lots of water, it's gonna help you A LOT.
Even if you're not a bodybuilder it will keep your system clean and will help you lose fat.
In case you are one, then, you should know that water will give you more strength, yes you heard me, water makes you stronger!
By simply drinking water your body will be hydrated, which will make it bear the fatigue more effective compared to an dehydrated body,  more accurately, 20% more effectiveness when your body is hydrated.

So, how could you possibly know you're hydrated?
That's simple, make sure that from the moment you wake up, to drink a glass of water from each half of hour, keep that way until you body will tell you it's time to get rid of the excess of liquids, so yes, just try to see if your pee's color.
If it's yellowish, it means you're not hydrated enough.
In case it's having no color, Voila, you're hydrated, and one you got into that point you will keep drinking 1 glass of water at each HOUR.

This things are not to be drasticly respected, there are also exceptions, in that case, just listen to your body and drink enough water.

You just became 20% stronger just by drinking water!