Its coz you get charged up very soon....

Electro static discharge (ESD) ...when you walk , / run/ or any activity ..ur body get charged and it tries to discharge them when you have a contact with another conducting medium...

its quite often and natural...

And why others dont feel it ....may b coz..your style of walking/doing the things are different as compared to them...

for eg..a person who takes long steps get less charged as compared to a person who take short steps...

hope its clear...