I am reproducing below two posts I added in my facebook page recently. I thought the topics were important and so am adding here. One is on Kamin, Karmayogi and Yogi and the other is the effect of bandhas on the spine. Hope you like them.
Bandhas and the Spine
It is common knowledge that yogasanas with vinyasas help to access every part of the skeletal system. Likewise the three bandhas help to access the important internal organs, muscles and tissues. But what is not well known is what the bandhas do to the spine
Bandhas and the Spine
Some yogis are obsessed with keeping the spine erect while doing the seated postures and while doing pranayama and meditation. Why so? Because with the straight spine they may keep the sushumna nadi straight and unimpeded for the aroused kundalini and the integrated prana to move upward. By mula bandha they (additionally) are able to keep the coccyx of the spine erect. Then the uddiyanabandha requires the pelvic and abdominal muscles to be pulled up and are also mandated to be pushed back feeling the low back. With this they manage to keep the lumbar spine straight. And the deep Jalandharabandha pulls the spine up and with kumbhaka they are able to keep the thoracic spine also stretched up. Any amount of external traction will not help the spinal stretch as much as is possible when the yogi goes into one's body and accesses the spine
Here is a picture of my Guru doing all the bandhas and straightening the back. He continues to teach us.

Karmi, Karmayogi, Yogi
Karmi, karmayogi and yogi are very familiar terms with yoga practitioners. A karmi is one who does karma or activity. All human beings are active in varying degrees and are thus karmis. Here we are talking about two types of activities. A karmi does activities to fulfill some desire. If the activity results in one getting what one wants there is a sense of good feeling, sukha meaning an agreeable internal mental space. If the activity does not produce the desired result there is a sense of bad feeling or duhkha. There is also another type of activity the karmi does. That is nivritti karma or activity done to get rid of something the karmi does not want. If one succeeds in this karma, then there is a sense of agreeable relief (sukha) but if not there is a very bad or vitiated mental space called duhkha. Thus the karmi rises with the tide and rolls with the punches all through life.
The karmayoga is one who by the study of the sastras like gita, yogasutra, upanishads, samkhya and also listening to teachers may be convinced that the real Self is not the empirical body mind complex as the karmi understands and functions but the non changing pure consciousness. Even though the karma yogi may not have the direct experience of the inner Self, the immutable consciousness, he/she by contemplation reasoning and studies becomes convinced about the nature of the Self and slowly but surely starts considering the purusha or the immutable immortal awareness as the Self and not the empirical body as the multitudes of karmis think erroneously. This understanding even as it is indirect is useful to function as a karmayogi. The understanding is known as anuman pragnya preceded by sruta pragnya
Karmayogi is a yogi doing karma. What kind of karma? Is it different from what a kramis does? Yes. Karmayogi performs one’s duties with the clear understanding that the real Self is unaffected by success or failure in the performance of karmas because the real Self is not affected at all, it is immutable. So without the anxiety of the results the Karmayogi is able to perform the duties without fear of failure or expectation. According to the Gita the advise of the Lord to the now changed to be a karmayogi, Arjuna, was to fulfill all responsibilities and not start (sarva arambha parityagi) new activities as the karmi does and become a complete yogi.
Then we have the Yogi. While the karmayogi has faith fortified with conviction of the nature of the Self, the Yogi endeavors to have a direct experience (yougika pratyaksha) of the Self and thus become free from any desire to achieve anything or to be freed from any other. But it requires a satvic mind with unwavering capability to remain focused called samadhi/samyma. Some born yogis have this as an innate capability and in samadhi (of the buddhi) are able to have a direct perception of the Self as immortal immutable consciousness. They are able to discern broad daylight between the Self or cit and the buddhi/citta or intellect. Others through kriya yoga and then ashtanga yoga bring out their innate but dormant capability of samadhi and achieve the final goal of Kaivalya.