My all-time favorite full-body exercise? Plank. Start at 10 seconds or whatever is your current edge. Up it 1 second each day. When you hit a time that goes beyond your edge, back off one second, then stay at that time until you’re ready to go back up.
Tips: Feel free to do planks on forearms or hands, knees down or up. Remember you’re trying to look like a plank of wood. Planks of wood do not bend in the middle or stick their bums in the air. Pull in your core, tighten your glutes, and push the ground away. You’re on your way!