Krishna says, "Know yoga to be that which scriptures call sanyasa (renunciation); nobody becomes a yogi without renouncing sankalp (motive/will)" (6.2). Earlier it was said that the pursuits of a sage are free from kaam (lust) and sankalp (kaam sankalp vargitaye) (4.19).
Krishna further says, "To the soul who is aspiring for perfection in Yoga, karma is said to be the means; to the sage who is already elevated in Yog, tranquility/quietude is said to be the means (6.3). When one is neither attached to sense objects nor to actions, such a person is said to be elevated in the science of Yoga, having renounced all desires for the fruits of actions (karma-phal)" (6.4).
Our belief is that karmas are motivated to get the desired karma-phal or else why would anyone perform karmas. A point to be noted is that if we don't know or haven't had an experience with something, it doesn't necessarily mean that it doesn't exist. Firstly, it's about analysing the experiences from our past karmas, which were done for fruits of action, and how most of them brought misery. Secondly, start performing small karmas without expecting fruits of action with shraddha (trust) on Krishna's assurance that such karmas are possible. Finally, the tranquility is about transcending polarities where praise and criticism become one.
Krishna repeatedly advocates unmotivated actions (nishkaam karma) and non-attachment to sense objects. It's about using senses as instruments to connect us to the outer world and for basic judgements for physical survival. Any attachment beyond that is the bondage of action (karma-bandhan).
For example, when we see a beautiful object, we can appreciate its beauty and move on which is non-attachment. Another is to get attached to it which generates a desire to possess it, leading to subsequent motivated actions.
Source - Daily World