It's okay to say, "no".
One of the biggest lessons I learned, as a leader, was to say "no" without feeling guilty.
As a leader there seems to be a never-ending demand on your time. Someone wants to talk with you. Someone else wants you to attend their meeting. Someone has a great idea for a new project. And on and on. It feels like the more you do, the more you're asked to do. If your plate is full, what they're asking doesn't take priority over what's on your agenda, and it doesn't absolutely HAVE to be done by you, it's okay to say, "no".
In fact, saying "no" can be an excellent delegation opportunity! "That sounds like a GREAT idea but I don't don't have the bandwidth to take that on right now. Could YOU head that up for us?" (You'll find out quickly just HOW good of an idea THEY think it really is! LOL!)