Selfish to Deny Help to Family or Friends?

This is Part 2 to the babysitting conversation.  Around the same time I made the journal entry that I posted yesterday, I emailed the following question to a Roman Catholic Spiritual Direction website.  Dear Father John, if Christians are called to charity, and we assume that our charity must cost us something (like time, comfort, or money), is there a time when we can justifiably deny a request without being selfish?  I'm an at-home mom and my friends often ask me to babysit for their children.  I always say "Yes", but only because it is difficult for me to do so, and I wonder if God is increasing my capacity to give.  Please visit the link below to see my question answered (in two parts) by Fr. John Bartunek.  By the way, this is a great website for all things Catholic and if you're interested, you can subscribe and get the daily post in your inbox.

http://rcspiritualdirection.com/blog/2011/10/24/am-i-being-selfish-by-denying-help-to-my-family-or-friends-part-i-of-ii-2

http://rcspiritualdirection.com/blog/2011/10/31/am-i-being-selfish-by-denying-help-to-my-family-or-friends-part-ii-of-ii