Debt is a promise of repayment with future work and energies.That is only the case if the debt in question is denominated in a liability you do not have monopoly control over.
When you go to the Bank of England with your £20 note and ask them to fulfil the promise on the front of it, you will get another £20 note. That is not future work and energies. That is an accounting journal.
Some debt is real debt. The rest is just an accounting liability.