Dentistry is exceptionally physically demanding.
I remember twisting my neck and back in dental school to look into a pts mouth and having an instructor tell me I "wouldn't be able to do that forever", and thinking that because I worked out and was healthy, it wouldn't be a problem. I was very hard on my neck and back the first several years out of school, as I didn't really focus on being very ergonomic, and often just had tunnel vision on the procedure I was doing.
I had loupes from dental school, but usually only used them for endo.
When I first started making good money at a corporate office and then as an associate, there were many 10-12 hour days running 4 chairs, and I had many days where I really torqued my neck out. I spend a fare share of time and money going to chiropractors and becoming a member at Massage Envy and getting massages twice a week, with extra focus on my neck and shoulders.
Fast forward to today. I own my own office so only I get to decide how hard I want to work and how many pts I will see on any given day, and how many hours a week I want to work.
I wear loupes (I own 4 pair of varying power) for 90% of my treatment, only not using them for removable pros. I use a loupe mounted LED headlight (Lumadent is my favorite, but also have DFV) at all times, in fact, I sometimes don't even turn on my overhead operatory light, lol.
The key to preventing injury for me has been limiting how many patients and procedures I will do, and wearing loupes with the maximum declination angle and long working distance helps me to maintain the best posture. I do most procedures with the pt laid back very far, and use a mirror extensively. I also exercise regularly and I am very active - this also is key.
To the OP - you are 30 now - are you done with prerequisites and ready to apply? Because graduating dental school at 34 or 35 is NOT old. The oldest grad in my class was 40 or 41. We had 2 females that started with my class that were in their mid to late 40's D1 year, but both washed out to the class behind us, and one ended up dropping out.