A person should ask his Lord for whatever he wants of the good things in this world and the Hereafter, and he should beseech Allah in Du'a, and not seek a hasty response, because the Prophet (peace be upon him) said:
"The slave will receive a response so long as his Du'a does not involve sin or severing of family ties, and so long as he is not hasty." It was said, "What does being hasty mean?" He said: "When he says, 'I made Du'a and I made Du'a, and I have not seen any response,' and he gets frustrated and stops making Du'a." [Bukhari]
The Prophet Muhammad (pbuh) said,
“Make dua to Allah in a state that you are certain that your dua will be responded to, and know that Allah does not respond to a dua that originates from a negligent, inattentive heart” (Tirmidhi)