Say the boundary in operational terms
Name the contact, behavior, topic, access, or commitment you will and will not participate in. For a message about how to ask friends to bring meals during recovery, use this factual base: explain the specific need, timing, duration, and what alternatives you have already considered.
Define any necessary exception
If an exception is necessary, give it one purpose, one channel, and a clear limit. Ask one person for one manageable form of help and make cost, transport, or follow-up expectations explicit. Make the immediate next step clear enough that the recipient can answer without reconstructing the entire history.
Respond to escalation safely
Do not disguise an emergency, guilt the recipient, or interpret a no as proof they do not care. Use professional, medical, crisis, housing, or emergency services when the need exceeds what personal help can safely provide. You do not need the other person to agree with a boundary for you to follow it consistently.