Reference: Shaykh Ibn ‘Uthaymeen – Kitaabul-‘Ilm
The Shaykh (rahima-hullaah) mentions:
So the expiation [of sins] is by good actions.
And this means that if a person fears Allaah (has taqwaa), Allaah will make it easy for him to do good actions with which he can make expiation [for the sins].