Sending someone a card is an act of love.
All the time you spend choosing the right card, you have the person you are sending it to front of mind. As you look for the words to express what you want to say, once again, you have that person in the forefront of your consciousness. Then you commit in your own handwriting a few words, that instantly reveal something of your own character and personality. In so doing, you have opened up to the other person. Now, enclosing the card in the envelope and writing their name and address, you acknowledge their status and place in the world. By adding the stamp and taking it to the post box, you demonstrate that you have taken some time out of your day just for them.
In this single act, you have shown that they matter to you, you have honoured and respected them, you have displayed admiration and appreciation of who they are, and you have extended a hand of support. This is the tangible expression of human kindness that they can refer back to as many times as they like. It builds their self-esteem, protects them from self-doubt, lifts their spirits and makes their day. It is a building block, a confirmation of friendship, of love, that increases in intensity and effectiveness the more often you do it.
Send early and send often!