An inspirational message for a get-well card is, “You have told me in the past to never give up. Now, I am returning those words of wisdom to you.” The quote shows both a personal connection and concern for the well-being of the person.
If the well-wisher is not in constant contact with the ill person, a good message is, “I wish you well a hundred times a day…. In my heart.” This shows the sender hopes the person gets better even though the two have not spoken to each other.
Also, humor is a great starting point for well-wishers. “You better get better. I’m tired of you being sick,” shows that the person cares about the other’s well-being and knows that laughter is sometimes the best medicine.