Add it to my age. Think of all the things there are yet to learn. That alone is enough.
Just one zero? Doesn't seem worthwhile to add it to anything. It wouldn't help me financially, I don't want to live to around 700 or 800 years, and anything else just doesn't seem worth it. Now if we're talking several zeros, bank balance hands down. I could do so much good in the community by donating or setting up trust funds among other things.