My friends complain I do not take the initiative to keep in touch with them and admittedly they have cause to complain.
I take no pride in saying only in the rarest of rare circumstances, I call them up. I have justified it to myself and others by ascribing it as my nature.
However, recently, (it may have been happening for a long time) I noticed some of my customers seem to have drifted away. They no longer call or email me any of their requirements. Since, this was effecting my revenue 
I thought some remedial action need to be taken. As a first step, I called a few of my most friendly clients.
Their reactions were on the expected lines. They made it plain that they were glad I called, however, where I was wondering why they drifted away, they startled me by enquiring what I am doing currently and when told, they were surprised to learn I was in the same line of business.
Leaving the business motive aside, this experience opened my eyes to the need to keep in touch with friends and business contacts, for they are glad to know that you are keeping well.
