Congratulations on your progress. I have one bit of advice from my full marathon. You may already know this. But I did a full walking marathon at age 59 after no exercise so I was terrified of it. I did it to raise money for cancer. The fundraising was also a challenge. I trained for 4.5 months and completed the marathon in just under 7 hours, which was my goal. A super marathoner told me at the outset that whatever my daily training goal was that I should never quit in the middle of it. If I set out to walk 3 miles or 2 hours or whatever, if I quit before then, I gave my brain the signal that I was a quitter and I would always be fighting the desire to quit during a hard training session. As someone who had to build up my endurance and fitness, it was the best advice I ever received. I may have had to slow down, but I never quit a training session. Good luck. See you at the finish line.