There's a book I like called The Happiness Trap. In it, the author asserts that humans were not meant to feel nothing but happiness all the time, and that to try to achieve that goal is futile. Instead you can connect with your goals and values that you find meaningful regardless of how you feel. So basically kind of what The Oatmeal is saying. But there's a bit more to it than that. You may not be able to feel happiness all the time, but you can feel peace. You can feel equanimity. You can reach a place where your emotions are free to do their own thing, and you no longer feel a need to control or fight them. It's possible to feel like a deep, deep lake, where the surface is rocked with storms and waves (uncomfortable thoughts and emotions), but the vast majority of you is still and peaceful, and you are not caught up in whatever is going on on the surface.