I learned to say "no" slowly but surely but I started a long time ago. It's different when it comes to one's own kids, though. Even so, there came a time.
Being that I'm a helper and nurturer by nature, it's so difficult to stop even though you know it's not really appreciated. It hurts! It's so frustrating!
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Psalm 119:105 Thy word is a lamp unto my feet, and a light unto my path.