It's not a question of how much to do, but a question of persistence. Do 4-5 groups every day, and rest for about 5 minutes between each group. 1-2 months will be effective, but your push-ups should be done standard. Otherwise, it's useless to do more. Get up quickly and slow down. The first time you do it, your arm will definitely hurt the next day. After that, you can reduce the amount slightly, but don't reduce it too much. Touch a little help. Generally speaking, you can exercise safely and no longer feel pain. In fact, it's not just doing push-ups. If you have a set of dumbbells, you can exercise all your muscles.