A forearm plank is a great place to start when working on core and arm strength. For those who struggle with a full plank, this pose can offer a feeling of accomplishment. Stay in forearm plank for 30 seconds, and when that feels manageable, work up in increments of 10 seconds until you can hold the pose for two minutes.
Begin on hands and knees with forearms shoulder-width apart. Prayer your hands together, or keep forearms parallel with palms flat against the ground (depending on what feels better on your shoulders). Tuck toes, lift knees off the ground, and step feet back. Reach through the heels and crown of the head, keeping a long spine. Engage navel to spine and breathe here (lower knees, if necessary).