If you continually go above and beyond the call of duty, often exceeding expectations, the day you stop, the people you have enabled will feel let down because you've spoiled them. Communicating limits and expectations is important. Giving your all doesn't mean depleting or damaging yourself. Don't be a martyr about it, they make horrid role models.
Often we just need a chance to stand back. The bumps we encounter usually serve to show us the (often hidden) motives we have had in giving. Once we've had a chance to see these things we can give our head a shake and carry on, most of us go on giving, but in healthier measure and with better, clearer motivation. I don't know anyone who has truly learned this easily.