Would you fill in a DNACPR for a healthy young adult who asked for one?

This is a hypothetical scenario, but say you had a young, healthy adult with full capacity who said they didn't want to be resuscitated. Would you complete a DNACPR (obviously, not if you a foundation doctor, question is more directed at the senior decision makers) or would you want a second opinion or psychiatry assessment before completing this?

And another hypothetical scenario - say someone had a DNACPR but came in after a suicide attempt with a shockable rhythm and had a good chance of survival with cardioversion/CPR? Would you still honour the DNACPR in that scenario?

Question triggered by someone who told me their (youngish) relative has a DNACPR in the context of a severe and enduring mental illness - don't know anything about their situation but the above questions came to mind.