Esther Derby writes about counting the cost on the job (including quotes from here). A quote re-mix:
When you're asked to do more with less, don't suck it up. The sure recipe for failure is to suck it up and try to do it all. You'll burn out, your team will resent you, your reputation will suffer, and the work probably won't all get done anyway. Prioritize relentlessly. Decide what you won't do.
“Suppose one of you wants to build a tower. Will he not first sit down and estimate the cost to see if he has enough money to complete it? For if he lays the foundation and is not able to finish it, everyone who sees it will ridicule him, saying, ‘This fellow began to build and was not able to finish.’
“Or suppose a king is about to go to war against another king. Will he not first sit down and consider whether he is able with ten thousand men to oppose the one coming against him with twenty thousand? If he is not able, he will send a delegation while the other is still a long way off and will ask for terms of peace.