I'm 40 have had desk job since 18.
I've had back pain forever, but the thing that has been really bad the last few years is "migraine" or tension headache that feels like it's coming from my neck.
The more I concentrate on my work, the worst I have it in the afternoon. This means I can rarely work a full 8 hour day without a nasty, nauseating neck migraine episode.
The only thing I have found that has helped a lot is quitting caffeine. I switched to decaf, which does not taste as good and only gives me a mild placebo boost each morning. I really miss my coffee, but it's not worth the headaches.