The heart becomes corrupt

The heart becomes corrupt in 6 ways: 

1. Seeking knowledge without applying it 
2. Committing sins in the hope of repenting 
3. Practice without ikhlas 
4. Eating the sustenance of Allah without appreciating it
5. Not being pleased with Allah's decree
6. Burrying the dead without learning from them
(Hasan Al Basri)

good deeds

Whoever completes these six good deeds will enter Paradise
Prophet Sallallaahu 'alaihi wasallam) said:

“Guarantee for me six actions and I will guarantee for you Paradise:

1. Be truthful when you speak,
2. fulfill your promises when you make them,
3. fulfill the trust when you are trusted,
4. guard your private parts,
5. lower your gaze,
6. and restrain your hands (from fighting).”

[Al-Bayhaqi, Sunan Al-Kubra, Number 11758, Sahih]