Great thread. I had zero musical experience other than a deep love of music. I *discovered* karaoke when I was 25 and sang pretty regularly for about 12 years. Despite having a really tiny range, I was actually able to knock out some good music during that time.
I was at AIT and had a super raspy voice from all the shouting when I started. My first night ever singing I was able to nail Janis Joplin's 'Another Piece of my Heart.' I received a standing ovation and decided that karaoke was pretty damn cool.
One of the last times I sang Karaoke was in the immediate wake of my divorce. I sang Little River Band's 'Cool Change' and brought several people to (emotional, not painful) tears.
Nowadays, I just serenade my wife in the car on trips and she likes it. Making her happy is more rewarding than a room full of strangers, so I don't karaoke anymore.
Music can be so amazingly cathartic. It can make your ups uppier and your downs less down (or at least you can share them with a room full of people who can share that moment with you).
It is never too late to explore music. I would urge anyone to take the plunge, whether it is piano, guitar, voice, or some other instrument. Hell tackle the didgeridoo and post videos on youtube. Whatever you do with music, you will grow from it.