I appeal to those desiring to protect their virtuous minds:

always diligently guard your mindfulness and introspection.

—Arya Shantideva

How do we guard mindfulness?

One is mindful to abandon wrong view and to enter and remain in Right View.

One is mindful to abandon wrong intention and to enter and remain in Right Thought.

One is mindful to abandon wrong speech and to enter and remain in Right Speech.

One is mindful to abandon wrong conduct and to enter and remain in Right Conduct.

One is mindful to abandon wrong livelihood and to enter and remain in Right Livelihood.

This is Right Mindfulness.

—Buddha Shakyamuni

How do we guard introspection?

To examine our thoughts, words, and deeds continuously, to determine if they are in accord with the Dharma, is to guard introspection.

Source: Mindfulness & Introspection