Saying "Thank You"

To say thank you means I accept. I accept the gift whatever it may be. The gift could be someone passing the salt and pepper my way, a door opened, a present or a compliment. Whatever the gift my thank you means I accept and acknowledge the giver as the source of the present. The giver has done something for me. The giver has helped, honored or bestowed something to me. So why do I never say “thank you” to myself?