You age. As you age, your cells age. Your
telomeres wear out. Even single-celled yeast age, giving birth to only a limited number of daughter cells. So how is it that each new generation starts fresh, unaged?
This is a great mystery - part of which is explained by the fact that your germ cells (which later turn into sperm and egg), those cells that will produce the next generation, are preserved with extra special care right from the start of your embryonic development. The non-germ cells, called somatic cells, make up all of the rest of you, and they age.