In need of some motivation!

First of all, congrats on your success of gaining back your health, and sorry for what you've been through. I was awwing while reading your story... it must be hard and you're really tough!

Talking about motivation, I'm not sure if my experience would do any help, but this is what keeps my butt off the couch and pushes me forward.
I used to diet and exercise just to lose weight, and losing weight was my only goal because I was tired of not being able to wear the clothes I wanted to wear and I hated it when family members and friends secretly implied that I was "too big." Anyway, the old motivation mostly came from the external environment- standard from society, pretty clothes, and maybe guys' attention. About 8 years ago, I was told by my doctor that I have multiple benign tumors in both breasts. Even though no signs of malignancy was found, I was told there might be unwanted changes and I was really frustrated- not just because surgery was suggested while I'm already flat at top (I somehow see those as fillers, I guess, lol), but I simply couldn't understand how this would happen on me, a person who doesn't smoke, doesn't drink, exercises regularly, eats mostly healthy food (still have a sweet tooth tho), and has kept a good record for basic blood tests (triglycerol level used to be really high). At that time, the doctor just said one thing to me: "there's no specific reason for why you're getting things like this but just keep doing what you're doing. Your lifestyle seems to be good. There's no guarantee for a cure, but a bad lifestyle could make things worse for sure."
I had multiple close family members diagnosed with cancers throughout my life; most of them passed away, but fortunately those in complete remission are still with us. Even though no signs of risk from genetic factors, I am still afraid of getting one someday later in life. That's why I was really upset with these tumors, even though I was told they pose no threat to my life at this point. I might be too nervous about it, but because of this condition, I now don't see working out or selecting food carefully as something pushed by external forces. I need them to make sure that I can make difference in my part and at least be responsible for the majority of what it shows on my health check-up report (sounds nerdy, but I'm proud of my HDL level, lol).

I now see being physically active and having healthy, balanced diet as a lifelong thing. I want to enjoy many things in life with confidence about myself, not just when I'm still young but all the way through my 90s (I hope!). It sounds weird and nerdy again, but I'm sure whatever we experienced in the journey of weight-loss, it'll become a very valuable reward that we'll have no regret later in life.

Hope you find the happiness and joy though this process as well!