That is the life tip of today.
It is actually very scientific. It has to do with you and your life changing plans. If you tell everyone around you that you are going to quit smoking or start exercising the chances are very high that they will answer in the common social way of giving you praise. That in turn will be interpreted in your body as success and you will feel good, hormones will be released making you feel happy. The effect is that you kind of got what you wanted, or what the body wanted, a reward and feeling good. Thus making it less likely for you to actually successfully go through with your plans.
That is why it is so common for people to only do their life changing business for a week or two.
The thing is, you can tell people, but tell people in a very cautious manner and with telling them not to give you praise. That IF you really want to tell them of your plans. I mean life changing stuff can be important for close friends or family to know about. This goes both ways though, if a friend tells you that he is going to quit drinking, well, don’t tell him that he is so cool for doing that. Tell him that he should be careful and give him your best wishes.
I actually found a cool TED talk about this. Check it out!