Start cautiously. Always produce.

Cal Newport writes:

I find it useful during this giddy season to remember that an emphasis on getting started, though currently popular, is not timeless. … Epictetus doesn’t reject action. But he believes commitment to a pursuit must be preceded by the careful study of what is actually required for success. He uses the Olympic games as an example. … For most budding ancient athletes, Epictetus implies, [the arduous reality of training] would likely dim the glamor of pursuing the Olympics. But not for everyone. As he then concludes: “When you have evaluated all this, if your inclination still holds, then go to war.”

Paul Graham says something similar in his essay on how to do what you love:

[I]f you have a day job you don’t take seriously because you plan to be a novelist, are you producing? Are you writing pages of fiction, however bad? As long as you’re producing, you’ll know you’re not merely using the hazy vision of the grand novel you plan to write one day as an opiate.

I suspect many people would find both heuristics useful: start cautiously, being realistic about what’s needed for success, and always produce. Together, they stop you pining for a life that’s not what you thought it would be and guide you towards one you’ll love.