If you ever scroll through your whatsapp groups, you may find that there are many groups created for road trips, movie plans, office outings etc, many of which never happened. Did you notice there were bunch of enthusiasts in the begining of these whatsapp groups, but most of them secretively escaped which affected the plan of others as well ? Ask any one of those escape hatchers - Why did you promise ?
Promises made just to make others happy rarely end up well. Most of the people will do anything to avoid immediate pain of saying "No". Since there is very little cost associated with saying yes, promises feel like real bargain. But while its quite easy to make promises, the real work is hard and difficult to do. Had it been easier, you would have done it immediately rather than making a promise.
Promises are like loans, you will have to pay interest. The longer you wait, the more they cost.