As a working mom, I cannot attend my daughter's piano lessons, much to the chagrin of her teacher. When he stressed the importance of being there, I had to gently remind him that he wouldn't get paid if I wasn't working. Yet, even though I stood my ground, the guilt crept in. What if I could be there, would it make a difference? Managing guilt is one of the hardest things we have to do. Here's how to help.