Rav Weiss discusses the commentary of Rav Yitzchok of Velozin for the first Mishna in the Second Chapter of Pirkei Avot : איזוהי דרך ישרה שיבור לו האדם? What is a path that one should pursuit?
The path one should pursuit, according to Rav Yitzchok of Velozin is the path that goes after his own heart. In other words, the path that one pursuits in action will ultimately reflect his own inner thoughts and values - כמים הפנים לפנים כן לב האדם לאדם. The person is judged based on their values, and what they have in their heart - one's values always come through even through the thickest of barriers, either verbally, action or even non-verbal communications.