I'm not an SJ - but sometimes I feel I have to take responsibility and/or pick up the pieces, which really blows because it is not my strong point.
After a while, you learn a very important concept and that is: SOMETIMES YA JUST GOTTA SAY NO!!!!
No. N-O. Two letters with a lot of power. You're not letting other people down; you are setting your priorities. You need what I call "YOU" time, and if people do not want to give it to you, screw 'em. You have to take it in order to be able to continue giving.
So if you notice people are being ass rats and not giving you the time you need to recoup, tell 'em you CAN'T. Be polite but firm. And if they won't give up, tell them to go "where the sun don't shine" because some people need a direct, straight answer.