"u think u can do these things but u cant nemo"

sometimes its really annoying to hear ppl contradict you....you say "aye i can do this" and then before you can even elaborate on it ..someone comes along and says "no you cant"...u push back again "yes i can" and you can either get one of two things.....a"no you cant" or "ok if you say so"......and really whether its a joke or not it some times hurts in a way...but most of my hurt and pain turns into anger and frustration....so take it as its frustrating me........it feels like someone is doubting wat you can do...and even if you prove them wrong..its always gonna be an explanation as to why....maybe im being to emotional about it or maybe taking it to heart too much but its like damn....dont you believe me when i say i can.....