Don't do it because you have to; do it because you want to. And if you don't want to, don't do it.
I've met a lot of people who think that sounds like dangerous and irresponsible advice. If people actually followed it, they think, it would lead to mass laziness, ignorance, and social breakdown.
I don't think people want to be lazy or ignorant. Nor do they want to sit idly by while their society breaks down. Those things don't actually feel good!
Sometimes, though, it can be hard to know what our real desires are. What we want is mixed in with things we think we should want, that other people want, and that we've wanted in the past but don't actually serve us any more. Not to mention, powerful memories of those times when we did what we wanted and got punished, teased or rejected for it.
It's often a lot easier to just do what we're "supposed" to do and avoid asking what we want altogether.
That said, I find for myself that when I do take the time to sift through all the noise in my head, I am heartened by what I discover. What I really want to do isn't just good for me, but tends to be good for other people too.
I want to tell the truth with kindness and listen with humility. I want to take good care of my body and my environment. I want to follow through on my commitments. These things aren't always easy or comfortable, but they are aligned with my deepest values, and when I act on them, good things happen.
Following the "do what you want" advice is only a problem when I don't sit with the question long enough to find an action that would really feel good, and instead act on the first idea that pops into my head (e.g., yell at the person I'm mad at, eat yet another slice of cake, renege on a challenging commitment, etc.). In those cases I'm not actually doing what I want to do, but rather running on auto-pilot. It's not a problem of bad advice, but bad execution.
What do you think? Do you have a good sense of what you want to do? What would happen if you did those things more consistently?