An opportunity presents itself. It's intriguing, but you're not sure if you should take it. So frame it this way:
1) What will this allow me to do that I can't do now? (And what am I willing to give up in exchange?)
2) What will this prevent me from doing that I would miss? (And what am I not willing to give up?)
Photo by Petros Pevel. Yay Flickr and Creative Commons.