After several months of little exercise and bad eating habits, my arms are now flabby and sad. I figure if I get back a little bit of muscle in my arms, which I was always proud of, it'll help me feel capable and healthy again as I work on the rest of my fitness.

Anyway, I'm not sure quite how to go about doing this. Doing real push ups (chest on the floor) is really a struggle for me now. I can crank out about ten, shaking and sweating. More than that is not happening. If I do easier, arms at 90 degrees push ups, I can do more, but I'm not sure which is more helpful. Does anyone know?

There are many other arm exercises you can do to tone up besides push ups. Google "arm toning exercises."

Push-ups are a great exercise. I think doing 10 is fine--do 2 or 3 sets of those. Weight bearing exercises are supposed to be hard. That's what makes your muscles adapt and get stronger. Soon enough you will be doing many more reps in each set.