In a retreat letter to your daughter, express your love, support, and encouragement in a heartfelt manner. Share positive affirmations and remind her of her strengths and abilities. Begin by greeting her and letting her know you are thinking of her. You can mention how proud you are of her for attending the retreat and taking this time for herself. Acknowledge any challenges she may face and offer words of encouragement. You can also share personal experiences or stories that relate to the purpose of the retreat and provide inspiration. Let her know you are there for her and believe in her. End the letter by expressing your love and well wishes for the retreat. Keep the language simple, genuine, and focused on your daughter's needs, growth, and happiness during the retreat.