The World Cup qualifying triumph in Cardiff on Friday night was the national team's first win since Chris Coleman replaced the late Gary Speed at the helm in January.
Morison said: "We always had the belief. We kept it from the games when we had been winning, even though we had lost a few.
"We have a great spirit and a great camp and we enjoy getting together.
"Everyone is turning up, which is fantastic, and we will carry it on until Tuesday night and hopefully we can put on a good performance in Croatia.
"We have always been behind Chris and I think we showed that we are a very good team. I thought we made Scotland look very average."