I say this to myself more often now than before. Do you put too much pressure on yourself to succeed? I have done that countless times. It's not about you being the Superman or the Superwoman in every situation. That just cripples you. No one can be everything at all times, all the time. You know?
I've learned, well, I'm learning, to compartmentalize every area of my life. Put things in order and deal with them in sections. It's crucial to maintain peace and this is one way to do so. It might mean that everybody won't receive a "Yes!" or "Ok." It's ok to say "No" or "Not right now.".
You aren't doing an Injustice to anyone but yourself when you don't work within limits. Having a chronic illness with continual pain and limitations has forced me into a place of structure. I can't do alot that I've done in the past but I can do my best. Practically, that's good enough. Stay strong!