The personal nature of this poem relates to the way in which it is a meditation of how Seamus Heaney, the poet, is following in his father's footsteps, though in a radically different way, which the figurative langauge employed in the poem helps us to see is not actually that different after all.
The poem discusses the way that his father and his grandfather cut turf and presents us with an evocation of their way of life and how they took pride in their work:
My grandfather cut more turf in a day
Than any other man on Toner's bog.
The poet remembers seeing how his grandfather worked, "Nicking and slicing neatly" and going "down and down." The poem ends with the determination of the speaker to "dig" in the same way as his father and grandfather dug, but with his pen, making a link between his writing and his rich cultural heritage. The personal nature of this poem therefore stems from the way in which the poet examines what he does and creates an imaginative link between his profession as a poet and what his father and grandfather did.