I don't remember this well enough to rate it.
Golden Years, on CBS
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The series was created by Stephen King, who I guess intended for it to become a regular series, but that didn't happen. (Nevertheless, I have always thought of it as a limited series; in fact it's quite possibly the first show I ever heard specifically called a limited series.) I'd definitely like to see it again someday, and write a proper review. It is on DVD, so I'm sure I will, eventually; though apparently the DVD's ending is different from what aired on TV. Oh, and I think I missed the end of the series, for some reason (maybe a VCR mishap, or a storm interfering with the reception, or whatever).
I don't remember the story in any detail, but it was about this old janitor named Harlan Williams (not to be confused with stand-up comedian Harland Williams). He was exposed to an explosion in the lab where he worked, and then started getting younger, and the government was chasing him or something. Actually, the main thing I remember about the series was that Felicity Huffman was in it. (I think this was the first thing I saw her in.)
Oh yeah also, I feel like this may be the first place I ever heard the song "Golden Years" by David Bowie, which the miniseries used as a theme song. So just about any time I hear that song, now, I'll likely think of this show.