First, strengthen your determination with sincere repentance to Allah, and then watch yourself according to the following method, which I have quoted from what Allama at-Tabataba’iy, the author of Tafsir al-Mizan, had written to a young man like you:
“First, in the morning, when you wake up, determine not to do anything that does not please Allah! Think well before deciding to do anything whether or not it benefits you in this life and afterlife! If it pleases Allah, do it; otherwise, leave it, regardless of whether or not you like it.
Second, do so until you go to bed at night, and then think of all you have done in the day, one by one. Thank Allah for your good deeds and pray to Him to forgive your bad deeds!
Third, continue doing this for several days. You may feel tired at the beginning, but then, it will gradually become easier for you and you will enjoy it morally and spiritually. Of course, the body follows the soul in comfort.
Before sleeping, perform wudu’ and recite the following suras: al-Hadeed (57), al-Hashr (59), as-Saff (61), al-Jum’ah (62) and al-Taghabun (64). If you cannot, you should recite al-Hashr only. With this action, you shall find that the pleasure of lawful things is sweeter than the pleasure of unlawful things. Then, you will laugh at those who pant after unlawful pleasures, and feel sorry for them and the mirage they walk in towards Hell.”
Fourth, before sleeping, perform wudu’ and recite the following suras: al-Hadeed (57), al-Hashr (59), as-Saff (61), al-Jum’ah (62) and al-Taghabun (64). If you cannot, you should recite al-Hashr only. With this action, you shall find that the pleasure of lawful things is sweeter than the pleasure of unlawful things. Then, you will laugh at those who pant after unlawful pleasures, and feel sorry for them and the mirage they walk in towards Hell.”
In the following tradition, Imam Ali (a.s.) mentions the qualities of the faithful and pious people, who follow sound reason and walk in the right path. Imam Ali (a.s.) says,
‘A faithful one is truthful in the worldly life, with an insightful heart. He keeps to the (moral) limits. He is a vessel of knowledge, with perfect thinking. He is generous, good-hearted, patient, and openhanded. He spends liberally. He is charitable, honey-tongued, and smiling. He ponders much, sleeps little, and laughs little. He is with good manners, free from greediness, and away from fancy. He is ascetic in this life. He looks forward to the afterlife. He likes guests. He is merciful to the orphans. He is kind to the young. He has regard for the old. He helps the needy, visits the sick, and escorts the dead. He respects the holiness of the Qur'an, prays to the Lord, cries for sins, enjoins right, forbids wrong, eats little, drinks little, moves with politeness, speaks with advice, and preaches kindly. He does not fear any except Allah and expects no one save Him. He is busy in thanking and praising Allah. He is neither negligent nor is he proud. He is not proud of the properties of the worldly life. He is busy thinking of his own defects away from the defects of others. Prayer is the delight of his eyes. Fasting is his job and occupation. Truthfulness is his habit. Gratefulness is his ship. Reason is his captain. Piety is his food. The worldly life is his prison. Patience is his home. The night and day are his capital. Paradise is his abode. The Qur'an is his speech. Muhammad is his intercessor and Allah the Almighty is his entertainer.’