'A teacher joked about my stutter, now I help others with theirs'
Callum's been told that he's suffered with a stutter since the age of seven.
He spent most of his life as a "walking thesaurus", thinking of words he could use to replace the ones he couldn't say.
From making orders in restaurants, to lessons in school and even saying his own name - Callum says his stutter used to affect "every aspect of my life".
That was until he discovered a group which helped him take control of his speech and inspired him to help others struggling in the same way all over the world.
You can find stories by other young people on the BBC Young Reporter website.