The core teachings of yoga and buddhism, or the realization of yoga and buddhism is very simple - Impermanence and Selflessness.
All kinds of different practices exist to serve as the tools for initiating and guiding the different minds to attain self-realization, of the direct experience and realization towards Impermanence and Selflessness, a.k.a. liberation from ignorance and its by-products, or liberation from the suffering deriving from ignorance and its by-products.
The different practices, or the different tools, are merely tools. Neither useful nor useless. They are useful if the selfless mind attains liberation utilizing the tools. They are useless if the mind doesn't attain liberation utilizing the tools, regardless of the attainment of many different side-effects deriving from utilizing the tools.
The best way to repay the kindness and generosity of all and everyone and everything that have been selflessly initiating, supporting, maintaining, training, mentoring and uplifting the selfless life existence of the selfless body and mind, is the attainment of self-realization.
Repaying the kindness and generosity of the selfless parents, the selfless companion, the selfless friends, the selfless mentors, the selfless teachers, the selfless nature, the selfless elements, the selfless energy, every selfless cell and atom and neuron, the selfless organs and sense organs, the complex selfless body structure and bodily system, the complex selfless function and modification of the selfless perceptive cognitive intellectual thinking mind, the selfless tools/practices, the selfless teachings/dhamma, the selfless universal consciousness, and the selfless manifestation of a selfless world of selfless names and forms, with the selfless realization of all these are selfless and impermanent.