You should not be so dependent on outward things; it is this attitude that makes you give so excessive an importance to circumstances. I do not say that circumstances cannot help or hinder—but they are circumstances, not the fundamental thing which is in ourselves, and their help or their hindrance ought not to be of primary importance. In Yoga, as in every great or serious human effort, there is always bound to be an abundance of adverse interventions and unfavourable circumstances which have to be overcome. To give them too great an importance increases their importance and their power to multiply themselves, gives them, as it were, confidence in themselves and the habit of coming. To face them with equanimity—if one cannot manage a cheerful persistence against them of confident and resolute will—diminishes on the contrary their importance and effect and in the end, though not at once, gets rid of their persistence and recurrence. It is therefore a principle in Yoga to recognise the determining power of what is within us—for that is the deeper truth—to set that right and establish the inward strength as against the power of outward circumstances. The strength is there—even in the weakest; one has to find it, to unveil it and to keep it in front throughout the journey and the battle.
Ref : Letters on Yoga Vol. IV