After a long break, I’ve started working out again. Every morning I sweat along with the cheerful woman on my exercise DVD as she calls out the standard encouragements: “You’re doing great!” and “We’re almost there!”

But she also says something I find profound: “Challenge to change!” In other words, if my workout isn’t making me uncomfortable it probably won’t give me the results I want. The idea motivates me when I’ve had enough, allowing me to do 10 (or two) more jumping jacks.

Yes or no? Should you or shouldn’t you? Should you apply for that promotion? Should you have children, or more children, or no children? Go back to school? Buy that house? Get married? Run for office?

Big life choices like these aren’t easy. Since they usually require weighing our own needs against those of others, they can be especially tricky for women. Many of us have trouble even noticing our needs. Most of the time our first instinct is to put others first, even if it means acting against our own best interests.