I think that the fact that I am pushing my limits and increasing my quantity of pushups is continuing to cause me quite a bit of ongoing soreness and pain.
I am also thinking that some of the advantages can be that it is way easier to carry my groceries.. and so some of these pay-offs can really come in handy, from time to time.
Yes it kinda pays off and you carrying groceries some long distances is part of it too

The pain Yeah! It will especially the push-ups it gives lower arm and abdominal pain from burning the farts. Although, I don't know your age but you can set some days in a week maybe two to take a break from it or you can just do less maybe 5 pushups or you can pick a particular week to do this five pushups for a week maybe a week in a month .
Then from my experience after pushups you try to extend your chest by standing between maybe two pole , extending your hands towards the to poles with you in between , now go forth and backwards feeling your chest expand and contract, you can do 10 to 15 of this as its more easier and this way you should expand your chest .
You shouldn't take it too far because of age I think it makes the heart beats very much faster whenever you are doing the fitness and you should eat more often to put up some little farts not too much chunks, you should try spicy food not before your pushups but hours afyter your pushups (spicy food increase fitness faster from exp) o eat spicy noodles alot

not too much spicy though
I think Jay already got that figured out for himself, from his recent comments he even talked about spreading out the excerise between the days to reduce the effect of pain for age ones or those that can't well endure the rigorous excerise.
Yeah those quick meals to rehain strength isn't such a bad idea especially when you going far distance for your work out, maybe a gym or somewhere more convenient that your house with a lot of motivators, I enjoy doing my work out in the gym with lots of neighbour hood friends, it's fun lots of talking and it's easy to push myself since many of friends have been I to pushups quite longer than me so It's just easier to do up to that 100 push ups.