It is not about doing tit-for-tat, but about placing appropriate value on those who mean so much to you. If what they did means a lot to you, then their person should also mean a lot to you, and how do you show that their person means a lot to you? You show it by how far you would go to make them happy too and to also let them know that you appreciate them, and you would always be readily available for them.

Taking a moment to give gratitude for things in and around your life is so easily forgotten. Reminders to do this are so important

Failure to do this may makes you to loose those you call friends and It's hard to experience a life without friends it's like living without love, it's simple isn't possible
Friends are the one who become a part of our celebration when we rise in life, and they are the one who become our support system when we fall and go through tough time. So we need them around, and not just only us, we need to render the same service to them, because we need each other in friendship

Thanks for sharing @olawalium