Next week I am going to be starting to play bassoon in a symphony orchestra. Every week we have a 3 hour rehearsal. Any tips on getting some good chops to play for 3 hours?

Wow, playing bassoon in a symphony orchestra! What an experience it would be! I'm no expert in bassoons or even in orchestras in general, but I do play double bass and have been playing in band for a few years. Our rehearsals are usually they're 75 minutes. I would love to play in an orchestra someday . . .

While I can't provide specific advice for you as a bassoonist, generally I would suggest that you take it easy at first and you'll eventually get used to it. Ask other members of the orchestra what they did to improve endurance. Others here probably can give more useful advice

I'm just curious: what orchestra are you playing for? Community? School?

I'm playing for the Binghamton Youth Symphony Orchestra. Heres a website if you want to check it out. http://www.binghamtonyouthsymphony.org