You Know You're Getting Old When

For the first time, you actually, truly understand the feeling of nostalgia.

nos⋅tal⋅gia [no-stal-juh, -jee-uh, nuh-]:

1. A bittersweet longing for things, persons, or situations of the past.
2. A wistful desire to return in thought or in fact to a former time in one's life, to one's home or homeland, or to one's family and friends; a sentimental yearning for the happiness of a former place or time