As with all recommendations, especially when it comes to exercise, ALWAYS check with your doctor to see what and when it's best to do any sort of movement activities.
With that, here are some basic and quick exercises and stretches that if done regularly can promote a healthy life style.
A plank can be done with your tummy facing down on either your elbows or your hands. You can also do a side plank with your hips perpendicular to the floor, one shoulder is above the other and while one foot is resting on the other. Set a timer for 15 - 60 seconds, hold your plank focusing on keeping your core tight and engaged with your back, hips, and legs all in line. Don't let your back arch and your hips sag down below the line between your shoulders and feet.
Do this set of 3 holding it for 15 - 60 seconds.
As it gets easier, you can make it more difficult by putting your feet up on a step or chair and or lifting one leg while holding your plank.
2. Push Up
Push up can be done facing down towards the floor with your hands and feet on the floor or with your knees and hands on the floor depending on your current ability. Some beginner positions are when you have your feet on the floor and your upper body is elevated on a table or the seat of a chair. An advanced position can be when your hands are on the floor and your lower body is elevated on a block, low table (like a coffee table) or the seat of a chair. Start with 5 push ups, then when those get easy with correct form, do 10 and progress from there.
3. Hip thrusts
Hip thrusts are when you're on your back with your shoulders and feet flat on the floor. You then lift your hips off the floor squeezing your gluts and hamstrings. You can make this more difficult by elevating your feet on top of a block or an exercise half ball (also called a stability half ball). If you'd like to isolate one sade at a time, in the same position lift one foot off the floor while lifting your hips. Start with 10 - 20 reps.
4. Table tops
Table tops are similar the hip thrusts, but your upper body is elevated on an exercise ball or chair. After you have lifted your hips to be in line with your knees and shoulders you hold that position for 15 - 30 seconds. Start with 5 reps of 15 seconds each.
This focuses on lower body and is done from a standing position. You want to bend your knees till your thighs are parallel to the floor and your knees should not move past your toes (you should be able to see your toes during the entire move). A correct squat should give you a feeling of sitting down in a chair, but before sitting you would stand back up. Remember to push your knees outward when squatting (this is called abduction, meaning outward or away) Start with 10 - 20 squats. You can raise the difficulty level by holding a 5 - 10 lb weight in your hands at chest height with elbows in.
6. Mountain climbers
Mountain climbers are when you're in the same position as a push up with your hands and feet on the floor. Your waist should be in line with your shoulders and feet. You tuck one knee up towards your chest and set your foot down on the floor, then your switch legs. This could happen by switching legs at the same time or one at a time if you're just starting out. Start with 10 - 20 switches or go for 30 seconds.
Always remember to stretch after your muscles are warm and especially after any exercise.