Verse 4.20: Abandoning all attachment to the results of his activities, ever satisfied and independent, he performs no fruitive action, although engaged in all kinds of undertakings.
As someone who spent numerous years studying Science, the scientific method is ingrained in my head. You start off with an objective, follow it up with a hypothesis, design the tests and run the experiment, collect and analyze your observations and draw a conclusion.
You can imagine my surprise when I realized that the process of bhakti yoga is actually very scientific! Specifically, the teachings of the Gita. What may throw readers off, as I personally discovered, is the fact that sometimes the expected results are given before the objective is presented in said text. It's important to remember at such times, that this is due to the fact that Arjuna was already following the path of bhakti and that's why Krsna didn't need to get into all the details.
It's kind of like coming into a conversation when you haven't heard the beginning. You can get an idea and start to surmise what the gist of it is, but if you don't have someone walk you through the background, you'll never get the full picture. For anyone who has read the Gita on their own and tried to make sense of it, perhaps you are nodding your head in agreement.
Again, this only serves to reiterate the need for a teacher who has themselves been taught the Gita and is practically applying it in their own lives. In fact, as we will hear shortly, the need to evaluate a genuine bhakti teacher is done by observing their behavior and noting the results.
Here the conclusion obtained from performing the bhakti experiment of "working without being attached to the results" is given: one feels ever satisfied and independent. Independent from what? From the rolling waves of happiness and distress. One instead feels peaceful and calm.
Now for anyone who has worked in or run labs, you'll remember that you need to perform the experiment a minimum of three times and get the same result three times for it to be valid. From personal experience, I'll tell you - it's very rare to get the same result three times in a row! That's because the procedure needs to be followed exactly and the conditions have to be replicated perfectly. The same holds true for the bhakti experiment of working without attachment to the results.
If one doesn't follow the methods and conditions outlined in the Gita, then it is only natural that the result will not be the same. Practically this translates to: don't give up! If the experiment doesn't work for you, it could mean that something is off. Don't blame the method (as any lab researcher/scientist will tell you!), but go back and analyze what you did.
The outcomes from this bhakti experiment vary depending on what you put into it. So if you sincerely want to get the results outlined in the Gita, such as those of peace, satisfaction and happiness, you have to follow the method given accurately. Good luck and feel free to share what you come out with in the comments below!