I'm "lucky" to have experienced chronic back pain for close to 10 years. Started a couple of years after graduation and got to a point where I couldn't sit for more than 20min or sleep for longer than 3 hours. It affected everything from my relationships, to my job (which I had to quit), to my mental state. I say "lucky" because I have mostly gotten over it recently, both physically and emotionally. So I can reflect on my time before pain, my time in constant pain and my time now.
Your response to chronic disease depends on your personality. Being stoic by nature, with strong background in sports I refused to accept I was disabled. I would not decline friends invites to play sports, even though I had to take a bunch of advil to last an hour of soccer. I wouldn't slow down on air travel, even though I spent half the flight in the bathroom where I could take a pose with less back pain. I had no empathy for myself and was refusing my condition. I regret that period and think it actually made me and my condition worse.
At about year 7, I started to accept my new, limited by back pain, self. I told my friends that I have the condition. It allowed me to vent periodically. Or make odd requests like asking to sit on side seat at a brunch table, so I can take frequent walks. I reorganized our house to be more forgiving for a back pain sufferer (basically moved everything I ever needed from the floor to waist level, so I didn't have to bend). Started taking days off work just to rest. Told my coworkers that I needed to adjust schedule because of the "back pain thing". I allowed myself to talk about it, vent about it and complain about I had a particularly bad day.
In the following years I was in more pain than before, but I actually felt better. I felt like I was accomplishing things I wanted and that my situation was just different, not hopeless. It no longer felt like I was disabled, but rather that I had a "thing". Everyone has their own: someone is taller, someone's brother beat them up, someone has a limp from a car accident, others grew up in poverty. It doesn't make them better or worse, it makes them who they are. My thing was that I had back pain. And it required me to make behavior changes to live a fulfilling life.
My advice is to evaluate your feelings to your condition and to yourself with the condition. Have you accepted it? Do you accept the new normal for yourself? Are your ok that some behaviors and experiences are out of reach? If the answer is "no" to any of these, finding peace with your new self should be the focus. It's not going to happen overnight, but it also won't happen without reminders and deliberate work.
When you have accepted the new normal, your happiness tank would start to refill with new experiences. The road ahead would not be easy by any means, but you would have the strength to walk it.