he thrill-in-the-last-minute Celtics have started to live a basketball life that produces fewer heart palpitations and gray hairs and more comfortable wins. Judging from the Celtics' high spirits following a 24-point triumph over the Hawks Saturday night, they could get used to it.

Sure, they will trot out their ''fight like wolves'' mantra when times get tough. And they will. They still will lose large leads and fail to sustain focus for four quarters. They will remember the feeling of a last-second, game-winning 3-pointer and overtime victories. And they will call upon familiar sources of energy to stage future comebacks.