There have been many times that I have felt like skipping, but since push-ups can be done really quickly, I just decide to do as many pushups as I can, and then I end up either doing close to my full set, or maybe I just end up doing 70% of what might have had been able to do. .and so that keeps the progress going, even maybe if I ended up doing 30% to 50%, that would probably be better than skipping sessions, yet once I start doing the pushups, I usually cannot stop at 50%, so I usually will want to do more than 70%, and so I will find if I get to 70% and I am continuing to have energy and the pain is not that bad, I just keep going and in the end, I feel good about the session, even though I started out by not wanting to do it.. and even dreading getting started.
I often encounter this and I see it as a challenge, it was hard for me to face it for months as I continue skipping and procrastinating with the thought "i will do it tomorrow " and tomorrow started to feel like some endless loop 
and i began to add weight 
I was only able face it by just giving a little try with the though"just little" and gets motivated anytime I try the little to do more, thus achieving the daily sets
, from little to achieving more than expected is a good achievement for everyday fitness and there's no fitness without pain IMO For sure, I am not in good shape, so it can frequently be difficult to continue to do them and even to start to do them.
I understand that there are guys who are even in worse shape than me, so surely they should still attempt to do just what they can and to continue to increase it. .and some guys maybe should not be doing full body pushups in the very beginning in order that they can get in some reps and allow the pushups to be easier.. because even if modified pushups are being done, it is likely that guys who do not exercise very much are still going to feel very sore and maybe even feel like they are going to die from doing 3-5 sets per day.. even if small number of sets of pushups from the knees or push ups standing against the wall but there likely would be some progress after a few weeks and even being able to do more and maybe even being able to progress into being able to do full body push-ups at some point.
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.