2. Pyramid Workout
This is a simple framework that can be used to create an infinite number of workouts. There are two steps: 1) choose exercise(s) 2) choose a number. You then start doing sets of the exercise, going up to the number you chose before going back down. For example, if I choose pullups as my exercise and 5 as my number, my sets would look like this: 1, 2, 3, 4, 5, 4, 3, 2, 1 (25 total reps).
Usually, I'll do this with 2-3 movements that use different muscles to minimize rest and maximize efficiency (e.g. pushups, pullups, & air squats). You can use this structure with any movement and you can easily toggle the difficulty by changing your top number.