The gift framing has a catch: gifts can be left in the box. Plenty of days get received and never opened — spent entirely on a phone, or on a version of tomorrow that hasn't happened yet.
Acceptance is the active part of that sentence, and it's harder than the joy part. Accepting today means accepting the actual one, with its slow meeting and its unanswered message, not the improved edition you'd have chosen.
One of these is roughly one twenty-five-thousandth of a life.
Do one thing today at full attention. That's what opening it looks like.