Incremental increases in distance and effort are the only sensible way to advance. Fitness doesn’t come quickly and you have to be patient, otherwise you can set yourself back or worse. I’m glad that you are not discouraged.
I was a fairly hard core cyclist until fourteen years ago when a motorcycle accident changed everything. I was back on a bike before I was off crutches. I had to ride without going out of saddle and I could only ride about 12 miles at a time, but coming from a wheelchair and many surgeries, that seemed impossible. Fourteen months after the accident, I rode a charity century ride.
From my wheelchair, I never would have thought that to be possible. At that time my hope was that I would keep the leg, that my spine would heal and that some day I would walk my dog again. All of that seemed unlikely and very far off, but it happened because I worked hard and progressed incrementally with short, obtainable goals,
I’m not suggesting that your goal needs to be huge. I’m just saying that with effort and a sensible training routine that you can probably reach your goals, whatever they are.
I am actually a happier cyclist now that I don’t race or feel the need to beat myself. Now, it’s about enjoying the ride, the scenery and the company on the days that I am fortunate enough to have riding companions.
Enjoy the journey. Set a big goal as a distant dream, but more importantly, set short goals and achievements within reach.