Krishna does not agree to award devotional service to merely anyone. Krishna can easily offer a person material happiness or even liberation, but He does not agree very easily to award a person engagement in his devotional service. Devotional service can in fact be attained only through the mercy of a pure devotee. — The Nectar of Devotion, Page 14.
The life of material existence is just like Hard Wood, and if we carve Krishna out of it, that will be success of our life.
Ungrateful persons are those who do not understand how much benefit they are deriving by the arrangement of the Lord.
Get yourself drowned in ocean of Chanting of Mahamantra, instead of money & wealth.
Always engage in devotional service with determination.
Trying to understand Bhagavad Gita with one's own mundane knowledge is like licking a bottle of honey from outside. Only when one becomes a devotee of Lord Krishna, one can understand Bhagavad Gita.