Theodore Roethke's past experiences greatly shaped his poetry and mental state later in life. His father owned greenhouses, which inspired poems like "My Papa's Waltz" describing his rough but soft-sided father. His father's death when Roethke was 14 had a profound impact, as he blamed himself and struggled with depression, which is evident in his introspective and depressive poetry like "Cuttings." Roethke's difficult past experiences uniquely influenced his inward-looking nature and mental health challenges.