If you haven't done pushups for the last ten years, it is very likely that you cannot do even one. In that event, you can gradually regain your ability to do pushups by pushing off from the foot of a flight of stairs. You can vary the difficulty by selecting which step of the stairs your hands push away from while your feet are on the floor beneath the first step of the stairs and while your back is straight. If you can't push yourself away from the stairs regardless of which step of the stairs you select, you can place your knees on a step and push away from a higher step.
Gradualism is the key. Both your arm muscles and your heart must be up to the job. Making a very easy selection is not silly. Reach high numbers on a very easy task before increasing the difficulty.
You may be surprised by how difficult it becomes to get up off the floor if you haven't tried to do this in years. Pushups on stairs is a way back. As you age, it becomes a safety issue.
You may feel that your arms are strong enough for what you normally do, but if you can regain your ability to do pushups, your health may improve. As always, check with your doctor about this and other home exercises.