Indeed, it is very true that it is hard to specifically train for the Camino but all long walks will accustom you to your shoes (so wear them & confirm their suitability on hopes). Even the concept of standing up all day will help because that is what will happen, you will be on yor feet for maybe 10 hours a day. You need to get used to it, as very few people live/work 'on their feet' nowadays. Wear those shoes all day when you are out and when given a chance, walk to where you go. (Backpacks and expected load can be for your walking hikes.)
If you can't do long walk, try some jogging (at any pace) which will stimulate your aerobic capacity and strengethen muscles. But the fact you do not jog in your Camino gear and shoes means the micro-alignment of muscles and ligaments will not be the same and foot weight bearing pressures are dissimilar, too. (I found the small muscles and soft tissue were the ones which made me suffer because I had not had enough time in my shoes and on my feet for long enough before doing the Camino. My particular difficulties were soles of the feet and shins. I believe, one for not having had enough time on my feet for 'training' and the other for heavy boots going up & down hills. All training will help but becomes pointless in the last week before starting, get rested and properly prepared at that time.
For the Camino, a little 'self massage' can be learnt for feet and legs. And maybe a fine way to recover is, at the end of the day, sitting (discretely) in COLD water for ten minutes, it stimulates the blood to go to the cooling muscles, which then helps flush out the 'overuse constituents from the muscles and aids recovery and relaxation. (At the end of a day I managed to sit in a cold stream, pool and even a water trough for cattle which was supplied by a flowing mountain stream. Odd but it helped when my legs were in 'crisis'.) Such pains & strains get better after the 10th or 12th day.. Hope I am not putting you off!
And last of all a muscle cream - Voltarol, can be bought in all the Camino pharmacies.
Be prepared, but also be prepared to enjoy and take each day as it comes. It is not a race but an experience which can and should lead to enrichment of your life (during & after).
God Bless, & Buen Camino !
Valdis.