I think not telling others makes it a million times harder because you get caught in a string of lies. I have done this in the past because I want to "keep the door open" just incase I change my mind, I didn't want to look stupid. To make yourself more comfortable for now, try taking the route of telling friends you're on a new fitness plan and there's no drinking for 60 days! That way, people won't pester you to go out and do things that you would ordinarily do - how many excuses can you really make?