Stick with the Dips that are likely to pan out, and quit the Cul-de-Sacs to focus your resources - Seth Godin

Risk, to some, is a bad thing, because risk brings with it the possibility of failure. It might be only a temporary failure, but that doesn’t matter so much if the very thought of it shuts you down. So, for some, risk comes to equal failure (take enough risks and sooner or later, you will fail). Risk is avoided because we’ve been trained to avoid failure.

Never quit something with great long-term potential just because you can’t deal with the stress of the moment.

Quit the wrong stuff. Stick with the right stuff. Have the guts to do one or the other.