Sentence:  By then one begins to <WSD>notice</WSD> the middle-age spread ; the gray hairs , the eyeglasses , bodies that are too thin or too heavy ; the fading signs of old beauty ; the athlete of by-gone years who wears a size 46 suit and puffs when he has finished a sentence of any length ; then , it is time to break it up and move on . 
Meaning of the word marked with <WSD> tags:  discover or determine the existence, presence, or fact of