The first yoga class with Shane Knox at Sage Studio he had us do a pose called Lizard. It has you on the mat on hands and feet, one foot back and on the toes and one foot forward foot flat on the mat. Your hands will both be on the big toe side. My legs immediately started shaking and soon I put my knee down because if I didn't I'd fall over. I was weak to that body position.
We all find that we are not strong to some activity and we practice and over time we gain strength. For me it took about 4 months before my Lizard pose was rock solid, then Shane found some variation of the pose that threw me under the bus and I had a new pose to practice and become strong with. Some days I can really feel strong to chair pose, and unsupported squat-like position, and some days it is super hard. But recently I was lifting a 55 gallon drum half full of canned goods into someone's car and it became a chair pose and the drum seemed to float into the car's back seat.
I was strong because I practiced being strong. You don't get strong by attaching the latest electrical stimulation device to your belly or exercising just one muscle group. You need activities that make the body work together in harmony. My core strength is so much better since starting my yoga practice that my day-to-day activities are easier to do and I am less fatigued and sore at the end of the day.
Join me in practicing yoga. See how strong you can be.