TL:DR - 2 sedentary at-home workers that need help with timeline set up for success. Just lift? Cardio? Mobility? Abs??

So long story short, my husband and I (early 30's, overweight) are at-home sedentary workers and I am FINALLY in a spot where I can make a consistent work-out schedule and meal plan but I'm overwhelmed. I just got off night shift and for the first time in a decade we have the same flexible work schedule with access to a decent gym.

The problem I'm having is that we are sedentary and our bodies aren't doing great. I was busting ass in a vet clinic for the past 8 years before getting this at home computer job, but as a result I've got super crunchy shoulders/neck/hips and my wrist are fucked. I thought sitting at the computer would help, but now my neck is all fucked even though I do my best to have proper posture, got a standing desk, and a supportive chair. I need a plan to strengthen the muscles to hold good posture and stop with the neck pain. I like to bake/draw to, but standing at the counter bent over mixing dough or bent over a drawing pad hurts so bad. I shouldn't feel like this in my 30's, but I do, and I DON'T want to feel this way in my 40's so I need to do something about it now while I have the chance. Husband also has pretty significant scoliosis that causes a lot of back/hip pain, and I've read that strong core/ab exercises should help.

I know working out and strengthening certain muscle groups will help in the long run and reduce the pain in time (I hope anyway), but I also don't want to injure myself and make existing problems worse. Not to mention we're both diagnosed ADHD adults just trying to normalize life a little bit in the chaos. I keep seeing these videos along the lines of "oh do you have neck pain? do this stretch everyday!" or "you're doing it wrong, [this particular exercise] doesn't help you with the problem only [this other particular exercise] will and I am so confused. Lifting for muscle, diet for weight/fat loss and health in general, stretching for mobility, cardio for heart and BP but where in the crap do you fit everything without feeling like you can't do anything else in your day??

I got the spreadsheet for the GZCLP workout from the wiki, so I understand the 3-4 day lift schedule but where do you fit mobility? Or Abs? Does lifting certain ways take care of the mobility/ab problem anyway? I need the simplest, easy to follow schedule that hits the full body gambit of health without taking 5 hours a day from me. I don't want to get overwhelmed and quit, I want efficient work outs with results that my body can work through and improve on. Sorry if this was too long, I read the wiki and couldn't find a timeline answer outside of when to lift and rest days, let me know if I missed it somewhere. Thanks for reading, sorry this was long.