With stuff which is largely affected by factors you cannot control directly (e.g. your health) I would be much less surprised.

"Praying for healing" was quite a common occurrence at my friend's church. I didn't pick that as an example because's it's a lot less straightforward. Praying for healing probably does appear to help sometimes (placebo effect), and it's hard enough for people who don't believe in God to be rational about health–there aren't just factor you cannot control, there are plenty of factors we don't understand.