Well done on your walk
& Happy Birthday
Also great that you keep an eye on everyone else - even though it's great challenge for you personally, it will be a team effort and the team will help everyone achieve that challenge. I bet the others are pleased you are with them.
I shall be guiding a small group of runners doing the Yorkshire 3 Peaks over Aug Bank Holiday - l've walked the route but not run it before, so like you I am apprehensive about everyone completing it safely and having an enjoyable time.
Preparation is key - don't forget to keep walking and exercising between your practice walks - try to build as much exercise, be it walking, climbing steps, carrying shopping bags into your daily life.
Swimming is fantastic exercise and lots of fun.
Good luck - it'll be worth it
Ian & Zen