High Plank: With the toes tucked and body long, place the shoulders directly in line over the wrists, place palms flat on the floor, mat, or towel. Keeping the torso as stiff as a board, hence the name plank, exhale with a strong SSSSHHHHHH sound. Keep the buttocks even with the back, not too much of a v shape and not swaying too low. Inner thighs are pressed together and buttocks tight. Start with 30 seconds for 3 rounds and build up to 3 minutes eventually.
Low Plank: Everything is the same here as in the high plank except the elbows and forearms are on the ground, both hands interlaced and interlocked including the thumbs crossed.
Seated to Standing: While sitting on a couch or hard chair, feet on the floor, stand up without putting your hands on the seat or arms of the chair. A hard kitchen chair is good for beginners, and a softer chair or couch will provide more of a challenge. If you want to add weight, hold a large water bottle (full of water). Do 3 sets of 20 of these.
Cat and Cow: Making the body look like a table, come to all fours on the floor, mat, or towel. The shoulders should be directly over the wrists, knees and calves on floor, tops of feet on the floor. Tuck the head and tailbone inwards, lifting the body from the belly button, shaping the torso like a rainbow curving upward. Pull the belly button to the spine and raise the back higher and higher, pulling the abdomen in as long as you can. This is cat. Then switch to cow. Release everything, gravity pulling the belly closer to the floor. Look up and tilt the tailbone to the sky. Do these 3 times, and then release the body into child's pose.
I think these are ideal for a short or long vacation, or visits to the in-laws (or out-laws).