A barrier or barricade is a physical structure which blocks or impedes something.
"Lack of execution is the only barrier on the road to success."
"Your task is not to seek for love, but merely to seek and find all the barriers within yourself that you have built against it."
"Don't allow negative thoughts to become a barrier on your path."
"Love recognizes no barriers. It jumps hurdles, leaps fences, penetrates walls to arrive at its destination full of hope."
"What barrier is there that love cannot break?"