Pilates/yoga were good for core strength and stretching. If you want to start at home Yoga by Adriene on YT is very beginner friendly. I was never a fan of cardio or strength training but I did a bit of that too (it was a gym with various classes and instructors).
Also got a dog, it's a great excuse for daily walks.
One day I realised I was actually resting my head on the headrest in the car and wasn't uncomfortable. Until then it'd never felt right and made my throat feel tight at the front. I still have a way to go though, I have back issues and you don't fix 15 years of bad posture in 3 years.
Edit: I'll add after reading the other reply, at the start it's a struggle just knowing what good posture is. It doesn't feel right and natural, because your version of natural has been modified. You don't know how it's meant to feel. I found that exercises which exhaust certain muscle groups helped a lot. They gave up some of their grasp and let other muscles work. After a really heavy workout sometimes my back felt looser and more mobile and this helped me learn how it could feel.