If you have a crush on someone then it means one of two things: Either that it is unrequited and the other person has no idea about it, or that it is someone totally out of bounds, such as a married person. Of course, it could also be both of these things, in which case: Oh dear!
The trouble with a crush is how consuming it can become. All-powerfully, exhaustingly, mind-numbingly obsessive.
If you are in close proximity to the person on a daily basis, then you will look at their every gesture as a 'sign'. A sign that they secretly feel the same way and would return your love if only...
The poor person only has to point at something the wrong way, or scratch their head at the wrong time and you are instantly on the internet googling for 'body language'.
And the hours, oh the precious minutes, which turn into hours and days dreaming about that person. What a waste of time when you could be doing something infinitely more useful like, oh, I don't know, actually working or something?!
Now come on. This unattainable person is not going to suddenly drop their (probably perfect) life and run off with you into the sunset are they? More fool them if they would. How long would it last before reality came a-knocking and you could see them for exactly who and what they were? Not a perfectly formed super-being, but a normal person, just like you.
This calls for some aversion therapy. The point is, that you need to lead your life. You know, move on with your existence - without being constantly struck by inactivity due to daydreaming about your wedding.
Every time, yes, every time that you think of that person, you must picture them doing something disgusting. From now on, you only think of them picking their nose. Not scratching, or politely wiping, but whole finger in, gouging something out.
Another thing you have to do, is that everytime you think of them, you have to super-impose an image of their husband's or wife's face frowning at you. So, think of them, a micro-second later, a big floating face appears frowning just like the Wizard of Oz. Pay no attention to the man behind the curtain!
If you don't know what they look like, make someone up. Put a bit of detail into it. Picture them going on lovely family picinics together, going shopping, washing the car. Get an image of them together first, then after that, just constantly frowning at you.
Another really good one is to see their children crying. Picture their cute little innocent faces tear-stained and heart-broken. Don't feel so much like having a crush now do you, you home-wrecker?
It is lovely to have a crush, especially if you think it is mutual, but if it becomes obsessive or there is absolutely no basis in it, then it has to be stopped or it will stop you. You will miss out on real opportunities which may be there, watching your every move and analysing your every nose twitch for a sign.