Copado...welcome to "the south side of 50 set..."
I too, have arthritis in my hips, knees and ankles. Though not overweight
...I maintain I am under-tall...I am of very stout build. I also have other chronic health issues and take several medications, some of which increase my sensitivity to heat and the sun.
As a result, I cannot do a Camino over the hot summer months. I am more prone to heat and sun stroke. The summer is when I travel to Santiago to work as a volunteer at the Pilgrim Office, usually for a month.
I cope with the fact that I KNOW the daily aches and pains will come once I have walked about a hour, each morning, by:
1. Slathering on Voltaren ointment, or other suitable analgesic, anti-inflammatory cream on the ankles, knees and hips. An alternative to Voltaren is "Fisiocrem" (purple tube / box), the spelling IS correct. The former is a straight out pharmaceutical product and contains paracetamol. The latter contains homeopathic ingredients.
Several folks with chronic pain issues in muscles and joints tell me the Fisiocrem works better than Voltaren. A good alternative to Fisiocrem is Luxoben Forte Ointment. The ingredients are similar...homeopathic. All three of these should be available at any Spanish farmacia. None require a prescription in Spain.
2. Lubricate my feet with a petroleum jelly-based product. Plain old Vaseline (Vasenol in Portugal and perhaps Spain) works fine for me. This reduces friction. In five Caminos, I have been blessed and avoided any blisters...not a one...yet. Callouses are my particular problem, and the vaseline helps with that issue.
3. Put on my thin, microfiber, liner socks first. Follow with ankles compression supports. Then, I put on my outer, cushioning Smartwool socks.
4. Put on both elastic, compression knee supports. I find the open kneecap stays in place better during the day.
5. Put on hiking / cargo pants. The ointment on my hips has dried and my underwear is on.
6. Boots are next, just before leaving my lodging.
7. "Breakfast" includes an appropriate dose of arthritis strength acetaminophen (Tylenol) / paracetamol, or whatever long-acting pain reliever you can take. My poison of choice is Tylenol Arthritis Strength caplets.
I take this AFTER eating something to avoid stomach upset issues. Also, the medicine will take an hour or more to act, just about the amount of time after I start walking that the pain starts. So, it heads off the worst of the pain and suffering early-on, before it can ruin my day. Sometimes, being predictable is good...
PLUS, as the medication is supposedly good for about six hours...the length of my walking day, I can safely switch to my beverage of choice vino tinto, or cold cervesa, after my shower and laundry chores are done in the afternoon, without fear of further destroying my liver...
Underlying all of this is that following every Camino, I carefully list things I either did not use, or things I mailed ahead to Ivar at Santiago (see 'Services by Ivar' at Santiago above). This has resulted in a lighter rucksack each Camino. I view it as continuous process improvement. I consider the Camino as a process and my accomplishment of it as an ongoing project. Hey, I am a retired analyst. Gotta do something to stay sane!
For example, after five Caminos and five centimeters of height loss due to spinal stenosis, I now have an Osprey Kestrel 38-liter rucksack. This replaced my "old faithful" Osprey Kestrel 48-liter rucksack, used for five years.
The last two Caminos, it was not completely full, and I finally "shrank" out of the M/L torso harness. While walking in Portugal this past May, I experienced shoulder and back pain, no matter what I did to try to better fit the Kestrel 48-liter M/L rucksack to my torso.
So, I wrote an e-mail to Osprey. They replied, advising me that my only choice was to downsize the torso harness to a S/M size.
When I arrived from Lisbon on the Portuguese route, in May this year, I donated my Kestrel 48 to the Pilgrim House at Santiago, and purchased a new rucksack once I got home.
Other than this regimen, I do what I can each day. Long gone are the days when I force myself, incurring more pain. Age has brought wisdom, in many facets.
Also, when I no longer have any more "get up and go" in me, and I am shy of my day's destination (usually where a lodging reservation awaits me) I go into the next bar / cafe and ask them to call a taxi to take me to the destination. This is usually perhaps 5 - 8 kilometers, depending on the weather, local conditions and my status.
One should not be disappointed or embarrassed by this. It is not cheating, except in the final 100 km before Santiago.
I view it thusly, if it were the Middle Ages and I was a poor pilgrim trudging towards Santiago, and a farmer came up in a horse or mule drawn wagon, offering me a ride into the next village, would it be a sin? I think NOT. So, take care of your body.
The cost for a taxi ride is about one euro per kilometer. I always cast about for others within hearing range who might be tapped out as well, and offer to share the free ride.
I hope this helps.