The two basic elements of being your most productive self that are totally in your control are sleeping and drinking water. If you're not sleeping enough you are basically killing yourself, but I'm sure you have all kinds of stupid justifications for that.
But drinking water? Come on. You can drink enough water, and if you do it will change your life. Not overnight, but over a long period you'll be healthier, happier, and more productive. This one thing, just drinking more water, will make you happier. Can you imagine? If I sold you a pill that was going to make you happy you'd be saying PLEASE GIVE IT TO ME, but the magic pill is just the water in your faucet! It's insane!
But let's be honest, water is also boring. Which is why I love infused water. Throw some citrus or cucumber in there and you have a bottle of that delicious "spa water" you see at fancy gyms and upscale offices. And you can have it ALL THE TIME, which means you'll DRINK MORE WATER, which means... yes, you will be happier. It's so easy, and this makes it even easier.
(I'm only selling the black version because the clear one is ugly.)