Krishna tells Arjuna in the Bhagavad-gita (2.47):
karmany evadhikaras te ma phalesu kadachana
ma karma-phala-hetur bhur ma te sango ‘stv akarmani
«Give your full concentration to discharging your duty and not to the result of your work. The result is with Me; all responsibility is with Me.» Higher calculation is like that. The generals say, «March! Go forward. Onward! You have to go. You are my soldiers; whatever I shall ask, you must do. You may die, and the victory may come afterward; that is not your concern. You are soldiers; many of you may be finished, but the country as a whole will gain.» In this way, so many important lives may be sacrificed.
And as soldiers, we have no right to calculate whether we shall gain or lose in the long run. There are two things we must be very careful about. We shouldn’t think that if we can’t enjoy the fruits of our labour, then there is no reason to work. At the same time, we shouldn’t think that we must get some share of the fruits. Remembering this, we should go on discharging our duty to Krishna. That is devotion, and that is the meaning of Bhagavad-gita.
Bhagavad-gita says, «You can’t change the environment. If you want peace, you must regulate yourself according to the environment.» The whole gist of Bhagavad-gita’s advice is found here: try to adjust yourself with the environment because you are not the master of the environment. All your energy should be devoted to regulating yourself and not the outside world. This is the key to success in spiritual life. Bhakti does not depend on the environment or on the dealings of others. It is ahaituky apratihata. Nothing can obscure that flow except our own ego. I am my own greatest enemy.
uddhared atmanatmanam natmanam avasadayet
atmaiva hy atmano bandhur atmaiva ripur atmanah
«We can elevate ourselves or degrade ourselves. We are our own best friend or worst enemy.» No force outside can check us if we are sincere. Of course for beginners, there is some concern about a proper environment for spiritual cultivation, but even that is also dependent on the nature of their sincerity, or sukrti: na hi kalyana-krt kaschid durgatim tata gachchhati. The assurance is given here by Krishna. He says, «I’ll be there to look after you in any unfavorable circumstance. I am omniscient. And I am omnipotent also. So, if anyone is directed towards Me, I’ll look after him.» And it has also been seen in history in the cases of Dhruva, Prahlad, and so many others. Sincerity is invincible. Even obstacles may improve our position if we can take them in the right way. From a higher angle of vision, it may be seen that everything is coming to help us.