Archery. Buy a bow and some lessons and perhaps a range membership.
Why? Archery isn't a sport that builds muscle, fluent body movement or produces a high heart rate that helps the heart. To me it seems a suboptimal hobby for a rationalist.
I'd also recommend laser eye surgery, particularly if you have any amount of astigmatism or are clumsy. Financed over two years, my cost is something like $5/day.
That's pricing the risk that it messes up your eye at zero. I don't think that's the right way to go about it.
Archery isn't a sport that builds muscle, fluent body movement or produces a high heart rate that helps the heart.
Reading novels, playing bridge, or playing the harmonica do none of those things either; would you recommend against these activities too for the same reasons? Hell, even commenting on LW does none of those things! ;-)
To me it seems a suboptimal hobby for a rationalist.
Well, what choice is optimal depends on what one's goals are, “rationalist” isn't a narrow enough category for this purpose, and in any event it's not like each person is only allowed to have one hobby at a time.
On ChrisHallquist's post extolling the virtues of money, the top comment is Eliezer pointing out the lack of concrete examples. Can anyone think of any? This is not just hypothetical: if I think your suggestion is good, I will try it (and report back on how it went)
I care about health, improving personal skills (particularly: programming, writing, people skills), gaining respect (particularly at work), and entertainment (these days: primarily books and computer games). If you think I should care about something else, feel free to suggest it.
I am early-twenties programmer living in San Francisco. In the interest of getting advice useful to more than one person, I'll omit further personal details.
Budget: $50/day
If your idea requires significant ongoing time commitment, that is a major negative.