Can a two-letter word really change your life?
Sophie Jones"Get out of your comfort zone." "Take no for an answer." "Do something every day that makes you feel uncomfortable."
If you've spent any time on social media you'll be used to seeing these motivational memes.
And you might have been seeing more recently thanks to the "rejection therapy" trend.
The most basic version involves pushing yourself to make a silly request or ask a question that's almost certain to get turned down.
Do it enough times, the theory goes, and you'll desensitise yourself to rejection and boost your confidence.
Others take it further, performing wacky, harmless stunts that will attract attention - and possible judgement from strangers - in public.
While it's not an officially recognised form of therapy, some people will tell you it's changed their lives.
But, professionals tell BBC Newsbeat, it's not for everyone.
One person who swears by rejection therapy is Sophie Jones.
The 22-year-old from Warrington says she was inspired to try it because she was always scared to speak up at work or make plans with friends.
She says she quickly learned that you might not always get the response you expect.
"I've realised that people do not like to reject other people," she says.
"It is very rare that I've got a straight-up 'no' from somebody - I always get an awkward laugh or, like, a 'why">The number of PSNI officers who have taken leave for anxiety and PTSD has risen in recent years.
