3 pages of great advice was accomplished, seems like most in here are aware of good health care practices, nice to see!
I've worked most of my life as a physical therapist (still am, but now I rehabilitate cars

), I hesitated being the first in here to chime in because I don't feel like 'prescribing' virtually with that much distance.
With that in mind, I'd like to keep all my directions bellow as very general since it's wise to be evaluated by a professional before taking any measure towards your health.
In order to add to what has been said, I felt like I've missed the word
Breathing. Proper breathing during physical activities is key for body positioning without generating too much stress on structures.
Abdominal breathing (Diaphragmatic breathing) is something we born doing correctly but as the time passes by (due diverse reasoning) we stop doing correctly without compensations acquired, mostly postural but also cardiovascular conditioning related.
I believe nowadays one is capable of learning simple breathing exercises through internet by it's own that will be a game changer not only in detailing but for general wellbeing.
While working, try to avoid holding your breath (Valsalva maneuver) like you're doing a medical exam, but exhale properly with the techniques learnt above.
It's always best to seek professional evaluation first because simple directions can not fit into your actual conditioning and can result in poorly ineffective results.
Keyword in this thread seems to be 'Core' conditioning, although it's very important and definitively should be done, I dislike this 'centralization of body' kind of approach.
Simply, try to tie your shoe without bending your knees or compensating with trunk. Independently of any core conditioning you may have, lower limbs proper strength and stretch (common to be a WEAK point in male subjects) are as important.
Another simple example, when you hold the polisher away from your body may 'look like you're hanging it with your arm and shoulder joint muscles', but you need as much upper / middle back scapulary muscles like rhomboids and trapezius also with serratus anterior (a muscle from ribs to inner scapulae). A severe deficit on this 'synergy' can be easily worked out with 'Push ups! and Pull ups!, true! How are you doing, soldier?
Core and lower limb both has the same importance in example bellow, not more, not less.
For this approach to reach any effectiveness a true professional looking and instructing what you're doing is necessary.
At least in Brazil, nowadays there are many people trained to work with methods like 'Pilates, RPG', and those people are generally what you'll need to be guided into proper posture, core, breathing, and whole body in one single 'method'.
It's something I'd not recommend doing for life (for the general standard health adult), but everyone should try at least 6-8 sections in life to better understand your most precious belong, your body.
I'm also one that discourage 'braces' like a postural belt, but depending on situation it may have it's use, don't need to 'crucify' the thing!
Again, just some thoughts, and feel free to ask what needed.
Keep in mind, like in detailing, you may get what you pay for. I'd definitively avoid cheap professional (they may instill swirls on you!).
Kind Regards.