Lea Winerman at the American Psychological Association explains what sets high high achievers apart from everyone else (via Lifehacker):

Grit is the disposition to pursue very long-term goals with passion and perseverance, sustained over time. So the emphasis is on stamina.

Self-control is related — we often measure self-control and grit in the same sample and find a strong correlation — but the difference is time scale. Self-control is the ability to resist momentary distractions and temptations in order to reach a goal, but the goal doesn’t have to be something that you’re pursuing for years or decades. You might have a goal of staying on an exercise routine or doing your homework that night. And if you fail to do that and instead sit on the couch or watch TV, that’s a failure of self-control. But the goal doesn’t have to be something you’re working on for years and years.
Or as Andy Warhol succinctly put it in regards to making art:
Don’t think about making art, just get it done. Let everyone else decide if it’s good or bad, whether they love it or hate it. While they are deciding, make even more art.
I associate my Three Don’t’s with getting shit done in life.