The poem starts out sounding sensible, almost like a lecture from a cautious adult: don't take risks, don't just do what you want, maybe skip the whole "live life to the fullest" thing. The quotation marks around that phrase make it sound like an overused slogan, something printed on posters. The speaker seems tired of it, or at least wary.
Then the last lines flip everything. "But honestly, / if you don't, / who will?" The speaker can't quite go through with the safe advice. The question is short and a little bare, and it suggests that if no one lives fully, something important goes missing. It could also mean that the speaker feels a personal pull, a sense that this is their one chance.
The mood is wry and quietly hopeful. It feels like someone talking themselves out of caution mid-thought, and the plain, casual wording makes the change of heart feel honest rather than preachy.