When it comes to a tight core, most people picture six-pack abs. But a truly toned core is much more than what you see on the surface. Deep within your loins, the psoas (pronounced SO-az) muscle group partners with other muscles to stabilize and girdle the lower spine, promoting proper body alignment.
A yogi is one who discovers that the greatest joy and peace of mind is within themselves, they see the exquisiteness of inner silence and their actions are for the good of others, whereas a bhogi is more concerned with their outer appearance, putting themselves first by enjoying and even over-indulging the mind and the senses.
We can infer then that happiness is enabled by an ability to create at will what we need, mentally, emotionally and materially. Although this sounds like a hybrid of the Law of Attraction and great portfolio management, to measure success in this way is really determined by our levels of willpower and self-control, which when combined lead us to self-mastery.