GOALS SHOULD BE TIME-BOUND

Setting a start time and deadline is important. This allows you to work out a plan to achieve the goal by breaking it into daily actions and marking your progress by acknowledging smaller milestones.

Hence, decide the timeframe needed to be able to do 20 push-ups on your toes, considering your current ability. If you can do 10 now, 20 can be a closer goal, but if you can barely do 5, you need more time to touch 20. But set the time limit...of course, you can push it ahead if you need more time. After all, it's you who decides your goals and plans.