Failed promises...

I had promised Nate that we would ride on a train.  Though I took him to the train museum and he loved it, we never got to take him on a real train.  I feel so bad that I promised him something that I didn't deliver.  Obviously I never thought that I would lose him.  Maybe it feels bad because I, in some way, feel like I failed in my promise to keep him safe.  I know that's a promise that's impossible to fulfill, just like the premise of "Finding Nemo".  Still, I think about those things that we tell our children because they need it, like "I'll always watch over you".  I guess I'm not really beating myself up over the train promise, maybe I just feel sad that I never got to see his smile if we had done it.