This will probably be too long--apologies in advance! I retired last July--DW and I walked the Camino Frances last fall. We started on 8 Sep from St Jean Pied de Port and arrived in Santiago de Compostela on 18 Oct.
There's an old saying: "Walk your own Camino." We wanted to walk from St Jean to Finisterre, but we got Covid about 10 days in and I injured my Achilles. So we had to take about 3 weeks to get over being sick and get our strength back up to resume walking again. That meant we ended up not walking the middle part of the Frances and ended our Camino in Santiago. We spent almost a week in Logrono quarantining and getting strong enough to travel again, spent a week in Burgos, moved forward and spent a week in Leon, then bussed to Sarria and resumed our walk from there. We ended up walking about 170 miles. We were disappointed we couldn't complete the entire Frances, but we also saw things and learned things about ourselves we never would've seen or learned if we hadn't had those challenges.
A few tips:
--Get a good guidebook.The ones by John Brierley are generally considered to be the best, and we used
his Frances book, but there are many good ones. Also check out
Gronze.com, an invaluable resource for maps and lodging on all of the Camino routes. And there are good FB groups for the Camino generally and specific routes, too.
--It's not like the Appalachian Trail or the Pacific Coast Trail, but you'll want to train even if you do a small walk. There are many hills and descents on most of the Caminos, some more than others. We were walking 9-10 miles/day in training, but where we live is very flat and we couldn't get the hill work. If (when) we walk another Camino, we'll do more gym work to get incline training.
--There are companies that will take care of booking your accomodations and doing the planning, but it's pricey and it's nothing you can't do yourself. (If you're a WDW enthusiast, you know that planning is half the fun!) If you want to stay in alburgues (hostels), you don't have to worry about pre-booking accomodations (although probably recommended from St Jean to at least Zubiri, if you walk the Frances). DW wanted to stay in private rooms, so we pre-booked our rooms, mostly through Booking dot com. We chose places that allowed for free cancellation within a certain number of days, which came in handy when we had to go with a Plan B.
--Don't feel like you have to walk the stages recommended in the guidebooks or websites. DW and I learned there are many places to stay "off stage" and sometimes that fits better with your style of walking. We found we
could walk 20-25 kms/day (our max before we got sick was 32 km), but we
enjoyed walking 12-15 kms/day, instead. So when we resumed our walk from Sarria, we planned our daily walks for no more than 12-15 kms.
--You don't have to carry everything you have with you. There are services that will transport your baggage forward to your next stop for a relatively small amount (4-6 Euros/day). That allows you to walk with a small daypack, saving wear and tear. We did that. If you do decide to carry everything you have while you walk, the general rule is to keep your pack weight to no more than 10-15% of your body weight, give or take.
If you're still reading this, I'll just say that even with the hardships we encountered, this was one of the transformative experiences of my life. It was
not the idealized Martin Sheen experience in The Way movie.

But we saw so much and met so many great people walking through northern Spain at 3 mph we never would've seen otherwise. DW and I had an incredible bonding experience doing it together. We're considering doing the Portuguese Coastal route in 2027. Feel free to DM me if you have any other questions, and please post a trip report here if you do it. Buen Camino!