If you tell a lie then you have to keep making up stuff to support that lie. after a while the amount of stuff you have to remember to keep the lie going is so much that you are stressed out.
If you do not lie..or if you come out and tell the truth you will be free of stress.
BUT - if the lie was to your friend that 'Yes - you like her new boyfriend' ..but you don't and he proposes to her and she is all happy...you NEVER EVER say: Ew
www...you know I lied to you and I really don't like him at all!!!'
.....because you will lose a friend.