A mature man should no longer associate himself with his childhood past. As a schoolboy, he used a trusty backpack to carry more books than necessary. Shoulders were raw and backs were aching from over-stuffed backpacks, but that was the price we paid when we were in school.
But we are no longer in school. There is no further need to use a backpack in the professional world. A backpack ruins your clothing and damages your professional image. Save the backpack for hiking; use a briefcase instead — whether it is a handmade leather briefcase or a hand-me-down — you can count on feeling, looking and being professional.