Help with DILD RC and mantra

Hey guys
just started here im working to try to get lucid. The problem us that whenever i try to do an RC during the day in the back of my mind im always thinking you arent actually dreaming. Ive been reading around and saw that thats a really bad thing to do.
Any suggestions?

I try best I can to suspend disbelief. One way is to remember a particularly vivid and recent dream and recall how it all seemed so real, never questioning that reality. If it was a dream then, it could be a dream now...

Ok thanks