Not every opportunity is the one that you should take. Sometimes you may get an opportunity to do something, for example to get a job, or to buy something quite rare. But should you take this opportunity? Firstly, do you have a goal, a dream, or just something you want to have? I'm hope you do, because living aimlessly is not a very cool thing. So, secondly you should evaluate this opportunity against your goal.
I find that more often than not, an opportunity that finds you, instead of you finding it, is not something you want. Moreover, marketers utilize this technique all the time: they make ads that scream, “LIMITED!” And people then think that it's their last opportunity to grab this thing, although they never needed it in the first place. That's why you need to evaluate every opportunity that is presented to you.
Today a very weird thing has happened to me. I have a couple of resumes on a job hunting board which I forgot about and never actually used. This evening someone called me and asked if I'm still looking for a job. I asked which of my resumes have they found, because I have two or three there. A woman on the phone appeared to be looking for it on the computer, but after about 30 seconds of searching she was not able to find it. How the hell could the recruiter not know what position they want the person for? However, she invited me to an interview (wtf?) on Skype, and surprisingly, I agreed. I just saw some kind of opportunity in it, I didn't think about the fact that I'm not even interested in getting a job or question her inability to tell me the position I'm applying for. Now I evaluated this decision and I know that I'm certainly not going there.