Always work out at your own level. If a standard plank is too challenging for you, use one of the intermediate levels (they go up in difficulty from 1 to 2). It’s OK to stretch yourself, but there are no bonus points for hurting yourself. Contrary to other strength exercises, a planking exercise is always 1 rep of each (regular plus both side planks). When you get stronger, extend your plank to last longer.
Rest on your elbows and your toes. Keep your body straight and your core muscles engaged. Hold for as long as you can.
All Levels: Side Planks
After each plank, do a side plank on each side. Rest on one hand/elbow and one knee/foot (same pair as you used for the plank).
Intermediate Level 1
Rest on your knees and hands, then do the plank exercise.
Intermediate Level 2
Rest on hands and toes, then do the plank. Alternatively, rest on your knees and elbows.