Life is a test and the Muslim has to meet the tribulations of life with patience and content of Allah’s Destiny. So, the real happiness can be achieved by feeling content with Allah’s predestination. The Prophet (peace and blessings be upon him) is reported to have said, “How wonderful is the situation of the believer, for all his affairs are good. If something good happens to him, he gives thanks for it and that is good for him; if something bad happens to him, he bears it with patience, and that is good for him. This does not apply to anyone but the believer.”
A Muslim is also required to set a good example for people in all aspects of life and thus he can lead a happy and successful life. Finally, a Muslim should do his best to come closer to Allah by making constant dhikr (remembrance of Allah), reciting the Qur’an, being beneficial to others, making du`aa’ (supplication) to Allah to grant him a happy and successful life, etc.
