Reggie Bush -- I'm Old Now ... And It Totally SUCKS (VIDEO)

Father time is taking a chunk out of Reggie Bush's ass -- by Reggie's own admission he's feeling ancient and doesn't sound thrilled about his upcoming birthday.

Reggie was out and about in L.A. looking absolutely decrepit (if decrepit people look super jacked) when we asked about celebrating his 31st birthday.

You can tell in this clip ... Mr. Bush is well aware over 30 means the "back end" of an NFL career.

Still, the free agent says he's totally healthy, listening to all offers and he's even open to a sort of homecoming.

Y'know he'll be playing somewhere ... if his wife has anything to say about it.