It's good to follow through on our words, yes. That's actually a scriptual practice blessed by God our Savior – we become imitators of Him because He keeps His Promises. It's especially important with children because they really trust us.
I think that all of us has a child inside of us that feels good when promises are kept. This is a message for Today is'nt it?......where so many promises are not kept with the busy rush and pace of life_ it's activity and responsibilities? For me, I said to The Lord once that I could not take any more of that and had to make a few boundaries.