how often do you keep a promise

I simply don't make promises I couldn't keep. If I have doubts that I could keep it, I always say "I'll try" or "I don't want to break your heart so don't make me.".

like you, i try to keep all my promises because i hate broken ones.. and if i didn't keep it, it means that something happened..

Well making promises and keeping them is your responsibility. Since you have made a promise you better keep it. If you do not then you earn the ire of the person you wronged. I think twice before making a promise. If I cannot keep it I try not to make the promise at all. If I have made one, I try to make an effort to fulfill it. If I cannot or there is a time delay I tell the person involved. I think its the safest way of dealing with situations. Afterall forewarned is forearmed.