Growing up in a Christian home, I remember learning "Your word have I hid in my heart, that I might not sin against you." (Ps 119:11)
I remembered that verse when I read another verse from the Psalms today (40:10), "I have NOT hidden your deliverance within my heart; I have spoken of your faithfulness and your salvation; I have not concealed your steadfast love and your faithfulness from the great congregation."
So, putting the 2 together, I should store up God's word in my heart, learning to treasure it. However, I should be ready to speak of deliverance, and God's steadfast love in public. So, while my faith should be and is very personal, it was never meant to be private.