A few thoughts from me, who's been there, done that, and had a whole wardrobe of greying t-shirts to prove it...
I suppose (at least when I was single) it was a little different for females...we didn't usually ask guys out. Had to let them think it was all their idea...but of course it wasn't...
Christine wrote:
It sounds like love if you feel like that

I'm not sure that we can say it's love, even if we find that the said girl/boy/whatever is on our minds, 24/7 - we are often at the mercy of our biology, programmed to find people very attractive. Sometimes it's just 'cos they are completely stunning, sometimes they remind us of a former love, sometimes they remind us of our parent (perish the thought, we'd say, but it does happen, more often than we'd like to think!)...
A long long time ago, I was convinced that Mr X was the one for me. It felt like love to me - I was completely floored...my friends noticed a change in me 'oh you're glowing, it must be love'...(it could have been all the exercise I was doing, the make up I'd invested in, the new haircut, all done to try and impress Mr X)...well, it never happened with Mr X, and it wasn't love, but good old-fashioned infatuation.
I think there's a fair bit of truth in the saying that fortune favours the brave, and agree that when we step outside our comfort zone, we open ourselves up to better things....
So I'd say to anyone 'go for it...give it a try'...but don't let anyone take up too much of your time/thoughts/emotions, if you're not going to do something about it....
I hope I'd take my own advice...if I was in that situation. However, I suspect I wouldn't!
As always, I believe that we end up regretting what we didn't do, not what we did...even if things don't work out like we hoped, we can always put it down to experience.