The Brain is an amazing organ for many reasons. One of its attributes is that it doesn't feel pain as its tissue doesn't have pain transmitting nociceptors. Neurosurgeons use this attribute to perform surgeries while the patient is awake.
Physical pain and pleasure are the results of the comparison with a neutral state of the brain. This analogy applies to mental feelings of pain as well as pleasure where there is a neutral point in all of us and the comparison is what gives the polarities of pain and pleasure. This background will help us to understand what Krishna says, "When the mind, restrained (nirodh) by the practice of yoga, comes to rest and in which he sees the self by the self and is thus self-satisfied" (6.20).
Coming to rest is the key. It is bringing that ever wavering or oscillating mind to rest. To achieve it, Krishna suggests restraint. The restraint doesn't mean the suppression of feelings nor their expression. It's witnessing them through awareness which can be easily attained by analysing past situations we have been through. Finally, it is seeing the self as the self everywhere.
Once we master this art of restraint, then we transcend the polarities of pain and pleasure to reach that neutral point or supreme bliss. In this regard, Krishna says, "When he knows the supreme bliss that is beyond the comprehension of the senses and can only be grasped by the intellect and once established he never wavers from the reality" (6.21).
This supreme bliss is beyond the senses. In that state, one doesn't need praise from others or delicious food etc. Incidentally, all of us experience this joy in moments of unmotivated actions or in meditation. It's about recognising and reflecting upon them.
Source - Daily World