High and holy ambition--to be a saint--is not opposed to holy humility--total reliance on God's grace. Exactly the opposite. Ambition without humility is ambition that fails. It is pride, which goes before a fall (Prov 16:18). Humility without ambition is false humility.
Peter Kreeft, Prayer for Beginners
ambition, grace, humilty, prayer, trust-in-god