The only reason many of us recommend variety is because it adds interest and works slightly different muscles. As many have said, there are quite a few different types of pushups. One of my favorites is “Hindu” pushups. Check out the varieties and maybe you’ll find a couple that appeal to you and increase the likelihood that you’ll stick with your program.
Ba-dum-bum. 
Whatever else you decide to do, you should throw in squats into the routine. Not with any fancy pants weights to make each squat really hard, just in your apartment where you do sit ups and push ups.
They’re more like sit ups, for me, in that you have to do quite a few to feel fatigued and appropriately sore the next day. But it can be a good workout.
It’s good to not neglect your legs, even if you’re interested in general fitness, not trying to add muscles anywhere.
That’s a good one. I still fantasize about doing the Jackie Chan/other Kung Fu movie thing where one sits as though in a chair but nothing supporting you – not that good at it. I have noticed walking/running pretty damned steep hills really gets the legs going – for some reason, it’s only my calves which look impressive. I think the quads only get a workout when running downhills, which I don’t like to do because it seems kind of dangerous on wooded paths with a bunch of tree roots and such. ETA that’s only for my experience – I know people whose quads really burn after a modest little hike/jog.
Isn’t there something like to preserve your knees when doing squats you shouldn’t squat too low? Its been years since I had a squat rack in my apartment, but I remember reading something like that.
But yes, starting something is better than doing nothing, and the initial answer of “do what you can and then add more as you can” is dead on. Your are exactly right to not start off overdoing it and to first worry about developing consistent habits.
The GQ answer to your op is, in the general case, “progressive resistance.” And all that means is that you start out where you are and then you increase as you can, by adding more reps, more sets, or more difficulty*, always hitting the point where you just do the last one with good form. No absolute number; it adjusts to what you can do as you can do it. Start where you are and always aim just a little beyond that and you are aiming at the right target.
And gong up and down your stairs a few extra times a day with your back full, or carrying some gallon jugs of water, is really an excellent idea. Even if you get looks from neighbors!
Good luck!
*For push ups, for example, that can mean changing position, doing explosive ones that you clap while in mid air, one armed push ups, ones with the feet flat against a wall, so on.
I like the “convict conditioning” idea. I’ll have to look into that. I’m open to adding variation, and that seems like a good type of source for Step 2.
As to how many I can do at a stretch, I don’t know—I’ve been doing sets. Probably 20 or 25? I’m not too good at pushing myself to the brink and beyond, more of a slow-and-steady sort.
Take a look at the standards for the US military Physical Fitness tests. They vary by service, but the Army and Air Force both require pushups, situps and a timed run. The Army runs two miles, but the Air Force only times a mile and a half. The Air Force scores number of pushups and situps done in one minute, while I think the Army gives two minutes (with higher minimum and maximums). The USAF also scores your waist circumference. Dunno about the Army.
This might be a good way to gauge your abilities to those of an average member of the US military. The test scores are broken down by gender and age, so make sure you read the right page of the chart.
US Air Force male aged 40-50 maximum scores: 44 pushups and 50 situps. Max run time 14:52 and a waist measurement around 36-37 inches will get you a score in the mid 80s. Passing is 75.
The USAF tweaks these numbers occasionally, so I think they must have a team of physiologists analyzing what a fit American should be capable of doing. I hope this helps.
Link to the Army’s standards. On the side they have suggested training programs to bring you up to army snuff: Push ups and Sit ups programs.
I’d take a look at ‘You are Your Own Gym’ and get some variety in there, rather than just Push Ups and Sit Ups.
This is why I do “stillness” training.
Instead of doing pullups, I just hang from a pullup bar for a few minutes, with my elbow joints at about a 90-degree angle. It provides the same benefits, pretty much, without the joint damage.
I also do handstand pushups this way. I don’t move, I just get into the handstand, get my elbows at about a 90-degree angle, and just hold there until I can’t maintain good form.
I know of a guy who does a lot of high jump kicks in martial arts routines, and he says that he stopped doing lower-body weightlifting because it reduced the necessary flexibility for those jump kicks.
Those sound great but do you really think our op is at the point he can do hand stand push ups or levers?
He could do the same thing, except in regular pushup position.
He could also do assisted pullup hangs, and/or pullup hangs with palms facing toward him, until he gets stronger.
Nothing to hang from—the shower curtain rod won’t bear my weight.
I will be following some of the recommendations in this thread for exercises to vary the routine with. I like the look of that “You Are Your Own Gym.” I think it just fits better with my self-image to have weird ad-hoc exercise equipment.
I tried timing myself for pushups in one minute this morning—I got to 20 in half a minute, and probably could have done a few more but pooped out.
How effective is this compared to actually doing the movements, same for other exercises; e.g. holding a weight in your hand straight out (physics would say that no work is done but your muscles need to counteract gravity).
It works about the same, IME. It might take a little longer to get to the same strength goal, but there’s much less risk of injury, especially if you stop the exercise each day before you lose good form due to muscle exhaustion.
The issue is isometric vs isotonic, as discussed here and here. FWIW.
Few fitness experts would advise an exclusively isometric program but many do include isometrics as part of the mix.
No offense, but I myself have seen noticeable strength gains with isometric exercise.
My guess is that the studies done on this are not of sufficient quality.
When I did calisthenics, I just did them on my own. No trainer or advice. No gym. So I may have been doing it all wrong and hurting myself in the process. Part of this time was in Hawaii, where I was active outdoors. Rode my book up to the top of Tantalus thrice a week. Rode 100 miles in the Honolulu Advertiser’s bike ride (not a race, I was never that good, you just had to go the distance for charity). I really was at the peak of my fitness in Hawaii.
Good form definitely matters. So does not overstressing your body; it’s better to build up slowly in intensity/load, and let your muscles/joints/tendons/ligaments/nerves get slowly acclimated.
I’ve heard that injury is one of the main reasons people stop an exercise program.