BG 5.19-21
Even here on earth everything is overcome by those whose mind remains balanced; the Eternal is incorruptible and balanced; therefore they are established in the Eternal. With Reason firm, unperplexed, the knower of the Eternal established in the Eternal, neither rejoiceth on obtaining what is pleasant, nor sorroweth on obtaining what is unpleasant. He, whose self is unattached to external contacts and findeth joy in the Self, having the self harmonised with the Eternal by yoga, enjoys imperishable bliss.