Why is it so hard to design for yourself?

For the last couple of days I have been trying to design a banner for this blog and I am finding it really hard to get the right look for myself. When I am asked to come up with concepts for a client the ideas flow so easily and abundantly but for ME I end up getting stumped and wonder how I ever do this for anyone else. I do have an idea in my mind but it just doesn't want to come out....maybe a cuppa might help? Any suggestions? I am determined to have this done by the end of the day so do drop by later and see what I have finally come up with!...maybe the pressure of a deadline might help me!