WHEN Wendy Postle’s two children were younger, saying “yes” gave her great joy. Yes to all those toys. The music lessons. The blowout birthday parties.

But as her son and daughter approached adolescence, yes turned into a weary default. “Sometimes it was just easier to say, ‘O.K., whatever,’ than to have the battle of ‘no,’ ” said Mrs. Postle, a working mother who lives in Hilliard, Ohio, a middle-class suburb of Columbus.

This year her husband’s 401(k) savings are evaporating. Medical bills are nipping at the couple’s heels. Gas prices are still taking a toll. Mrs. Postle recently decided that although she and her husband had always sacrificed their own luxuries for Zach, 13, and Kaitlyn, 15, the teenagers would now have to cut back as well.

“No” could no longer be the starting gun of family fights. It would have to be an absolute.

“I tried to tell Kaitlyn, ‘We’ll get the Hollister jeans at a thrift store,’ ” Mrs. Postle recalled. “She got angry and said: ‘That’s gross! Other people wore them!’ ”