Going deep, not wide
It's tough. Knowing when to quit (or change directions ever so slightly as I like to think of it) has to be one of the most challenging tasks for a lot of people. There's so much emotion in starting that quitting feels just plain loserish. I mean, no one really enjoys telling the world, "Hey, yeah. I'm a quitter."
I don't know when the exact moment is that you know when to quit and I'm sure the signals are different for everyone, but I do want to make this observation:
For some of us, focus is really easy. Doing one thing really well isn't the challenge; it's breaking out of your shell and trying something new that poses difficulty.
But for others (myself included) it's diving in deep that creates some ugliness. Feelings of entrapment, clautrophobia, fear of failure or boredom and really of missing out plague these decisions of pushing forward into the dark woods.
There's something to be said for moving forward on an unmarked path where the wood is thick and the light is minimal. Intuitively there is a clearing in the midst, a break where light, space and air flow freely.
Stopping in the woods is ok but to live there isn't sustainable. I much prefer the clearing with the option of venturing yet again into the woods if I so choose.
I'm not saying you cannot change direction; I'm just saying forward should be the goal however it is that you need to get there.
P.S. Had to say it: the title of this post has "that's what she said" written all over it. If you were in the room with me right now as I write it you would of heard me say "TWSS" to my dog Luna.