You should take some time to re-evaluate anything that you might be holding back from yourself. There can be many things that you decide to 'think about later' that can subconsciously effect you and your state of mind.
If you are just more sensitive to things, then you are - There's no way to stop it unless you begin to try and accept what's happening that may be causing you to cry, then maybe you can look at it and see that its not so bad?
If none of what I've put so far is helpful, I'm sorry. I guess one last thing would be not to get your tear ducts removed! You need them in order to keep your eyes lubricated!! If you were to, they would get very dehydrated and you would most likely have to take eye drops for the rest of your life (which could become incredibly painful if you let your eyes dry up too much). Hope this helps