When you feel you want to be with that person your whole lifetime. You want to spend as much time with them as possible, even if they text you "thanks" for wishing them happy Birthday and you feel happy that they even texted you. You just want to crumble from your emotions be sure it's also painful to have a crush. You just want to tell them how you feel for them, but you know it's a 50/50 chance of them liking you back. You want to spend all the time in the world with them. You will cherish every moment with them. You always think about them. You will want to look nicer for them. Just know, having a crush is the most wonderful yet painful experience in your life.
My crush texted me the other day and asked what I was doing.