5.19, Sloka 19, Chapter 5:

This is a sloka of hope. Lord Krishna gives hope that those who are situated in equanimity will achieve paradise/heaven in this very life and they need not wait until the next birth. The only qualification given is equanimity. Equanimity to pain and pleasure people will experience the happiness in this present world. There is one more sub qualification added here. It is along with equanimity, people should be absorbed in the absolute truth whatever it is. If they are absorbed in the absolute truth, then they become free from samsara. That means the results of the work here on earth do not matter to them. They keep working completely absorbed in the absolute truth.

Thus it is clear that these two qualities, equanimity, and absorption in the absolute truth will take out the person from this world and make him experience paradise in this very life.

Will we not lose our concentration if we concentrate on absolute truth when we are doing work? It is meant here that you get completely absorbed in the work you are doing, whenever there are some distractions remember whether that will take you closer to your work or away from your work. If a person is absorbed in complete truth always then it will be easier for the intellect to make decisions, otherwise, a lot of willpower need to be generated to take decisions. Right decision making becomes easy if we are absorbed in ultimate truth.

5.20, Sloka 20, Chapter 5:

Continuing the qualifications Lord Krishna adds two more qualifications. Sthira buddhi means steadfast intellect. And assamudho: free from delusions.

Sthirabuddhi means there is no confusion in the mind of a person as to what is absolute truth. He is not confused into where the actual happiness is. Is it in the present world in the interactions with people/objects or is it inside a person living a life of virtue. I think that once the person has a fixed intellect, then decision making is easy. There will not be confused as to which path to pursue, which bridge to burn and which bridge to pursue. Things become clear if the mind is steadfast. Also, the person should be free from delusion. He should not be under the illusion of Maya. He should be able to differentiate between things of Maya and things of truth. A person having these qualifications and when he is absorbed in the ultimate truth, then he doesn’t feel bad when bad things happen to him or feel happy when pleasurable things happen to him. He basically becomes equanimous.