Joe:
This is an outstanding dialog. I hope you read and take to heart all of it. Many folks have provided just about all the useful advice and information you need.
The final decision is up to YOU. I will try to NOT repeat what was said (correctly I might add) above. Here are some points and observations to consider.
On the Camino, we have several "rules." We call them "the Camino Rules."
Rule #1 - "Everyone walks his or her own Camino...mine is not to judge the motivation or manner of another's Camino. Judgement is left to the Supreme Being."
Rule #2 - "The Camino provides..." This means that assistance, or just a break in the weather, usually happens about when you need it the most. Just live in the moment and you will be fine. Enjoy the walk and smell the flowers... Appreciate the others around you all heading in the same direction.
Rule #3 - We accept that "St. James (the patron saint of the Camino) works in strange ways affecting pilgrims. Sometimes his methods and actions are just weird." Just BE, and let the overall ambiance overcome you.
The transformative affect is amazing. Be alert to the "micro-miracles" that occur around you every day. You do not have to be a religious person, or a Christian to realize these benefits.
You will meet people from all over the world, from every political, faith and cultural persuasion. If you are a military veteran, you may even meet former adversaries or enemies, this time on neutral territory. It is a small world...
English seems to be increasing as the defacto second language along the Camino routes. But, do try to learn at least some basic phrases, questions and answers in Spanish, Portuguese or French. "Please" and "thank you" go a long way in breaking down language barriers. Many languages are spoken by pilgrims from all over the world.
Yet, all pilgrims have the same thing in common, a shared pilgrimage to Santiago de Compostela. Each pilgrim's reason for walking may be different, but all will be transformed by the experience.
Overall, the Golden Rule abides; "Do unto others as you would have them do unto you..." The rest is easy...
There are other "rules." But they are less important things addressing albergue etiquette, cultural and political sensitivity, etc. You will learn them quick enough if you just listen, help others in need, and go with the flow.
You must FIRST come to understand and love / accept yourself. Empathy for others comes after that. Cut yourself a very big break. Just BE.
The Camino will heal and help. Once you reach Santiago, presuming you will be on the road for a month or more, you will not recognize the new you. Just trust me and all of US on that. We have all been there and done that...
Weight Issues and Conditioning:
You are not the first, nor will you be the last "stocky" person to ever walk the Camino. I am 5'10 and now weigh about 230 pounds. I start my fifth Camino from Lisbon to Santiago on 27 April. I previously walked the full
Camino Frances twice (2013 & 2014); Porto to Lisbon in 2015, and portions of the Madrid Route in 2016.
For more than 25 years I was morbidly obese, well over 300 pounds, and had a bariatric lap band installed in 2005. That helped me lose 90 pounds but decades of wear and tear on the knees from the weight and my career essentially knackered them. I have nearly no menisci cartilage in both knees. I remain technically obese, but otherwise completely healthy. I hope to turn 64 in June.
Just FYI, each March I schedule my annual physical, blood work, dental and optical examinations to ensure I am "good to go" for "Camino Season." This year, I got the green light. While we all die someday, I am not looking forward to my personal roadside shrine along the Camino, not at least just yet. You will see when I mean as you progress.
So, each day on Camino, I suit up like a knight going into battle. I lubricate my feet to reduce friction and blisters (I have had NONE in four outings), apply prodigious amounts of Voltaren ointment (reduces swelling and pain), put on elastic ankle and knee support braces, and THEN socks and outer wear. My "vesting" process usually takes 15 minutes. Only after all that, am I ready to walk for the day.
Every problem has a solution, every obstacle has a detour. If you cannot finish the day's planned walking and have a reservation waiting for you. go into the nearest bar / cafe and ask them to call a taxi to take you to "x."
It costs about one euro per Km. It is analogous to being offered a lift in a farmer's wagon back in the Middle Ages. Neither action is a sin. You only need to be scrupulous about the final 100 m, from Sarria, on the French Route. Get two stamps per day from there, from your lodging and a cafe during the day.
If you stay in albergues and sleep as you go, do so. Walk at YOUR pace, not others. Listen to your body. There are farmacias in nearly every town. The pharmacists have seen it all, many times. They can sell you products that would require a prescription here in North America.
FYI, the only training I do is to ensure that any new footwear is well broken in to eliminate blisters. I usually do some treadmill walking and weight work on my knees to preclude pain later. The first week of any multi-week Camino is essentially a "shakedown cruise." You do train as you walk.
After the first week of daily walking, things start to get better. That hill in the distance is not as scary as that first climb out of Saint Jean Pied de Port was, when you were hacking up your lungs... It is NOT that bad. The worst part is the first eight km. After that, it undulates up slightly and down.
Packing & Pack Weight:
Finally, do not carry more than you need. As a "Rule of Thumb" try to adhere to the gross rucksack weight, sans water, of 10 percent of your body weight or 10 kilograms (22 pounds). For what is is worth, the best I have the done is 12 kilos. But, I have to carry protein powder nutrition supplements to my diet. One week = one pound. Then, there are the medicines and nutrition supplements I must carry... Overall, when I start out from Lisbon on 27 April, I will be carrying about three kilos or six pounds of nutritional and medicinal support, for a nearly four week Camino.
As a consequence, I have become very skilled at paring all other carried weight down. I shop for ultralight gear, preferring siliconized nylon where possible. I use simple, one-gallon or three-liter ziplock bags to organize and keep waterproof my belongings inside the rucksack.
EVERY item I choose to pack and carry MUST have at least TWO alternative uses. Single-use items are luxuries I must mostly do without to save weight for the pills and powders. I replace paper books, guides, maps and other stuff with files on my iPhone. I have become adept at converting all manner of files to .pdf format. Bytes of storage weigh nothing.
There are threads, ad nauseum, on the Forum about packing, gear choices, etc. So I will no go into further detail here.
In summary, just do what ya gotta do to make this happen. You will be pleased with the results.
I hope this all helps. If you have questions, please feel free to send me a PM (Conversation).
I wish you "buen Camino" (ES) or "bom Caminho" (PT), depending on where you go.
... onwards and upwards
I kind of ate and drank my way across Spain 
