In our lives, whether we like it or not most of our decisions are based on emotion rather than logic. We may be able to rationalize a decision once its taken but the triggers for it are usually rooted in our emotional states. The more intense the emotions the stronger the inclination towards a certain decision. This can be true for even the small preferences that we have. For instance, the craving for a certain kind of food is usually because of certain happy memories of childhood associated with it. In Yoga we should make use of all possible opportunities & tools for evolution. Hence it makes sense for a yogi to be able to effectively utilize emotion as a tool for growth.
What should then be the emotion which helps in spiritual evolution? The Bhakti traditions talk about the bhava that human beings need to inculcate towards the divine. The bhakta celebrates both the joy & sorrow in the separation from God and revels in it. The joy is because bhakti can only happen in duality where both God and bhakta are separate. The sorrow is because there is also an intense longing to merge into the divine. This counterplay creates a strong emotional bond with the chosen deity. There are accounts of Bhakti saints who start to see their ishta in everything. Many a times their absorption in their ishta is so intense that they forget everything else around them. When someone reaches a stage like this, it is obvious that an enormous transformation has happened in their being.
There are a lot of schools of yoga who differ from each other in their approach. However they almost all agree that cultivation of bhakti is very important if one is desirous of accessing the divine. Bhakti can only happen with purification of bhava. In my experience, among the most important things that the practice of kriya under the guidance of Guru enables is this purification of bhava. There are so many experiences both good and bad that I have had throughout my life that it was difficult to create a certain purity in bhava. Hence it was important to unlearn that conditioning before I could feel a deep longing for the divine. The energy from kriya along with Guru kripa helped burn these unproductive thought patterns at the neurological level.
It is important to always keep in mind that Kriya is a tool and not the goal. Many a times we end up mixing the two. I myself have done this where I felt that I should learn the best type of yogic practice and went after finding the best techniques. This thought process is a lingering remnant of the ‘doer’ mindset where we feel the need to do something to get something. While there is something to be said for discipline in sadhana & rightful actions, in the spiritual realm things work a little differently.At my current state of evolution I feel it is best to live in a bhava of devotion to Guru & the divine and let transformation happen at its own pace.