But becoming a priest was something he wanted to do for as long as he can remember.
The boyish-looking young man from Rock, Co Tyrone, was ordained alongside Thomas McHugh (26) from Castledawson, Co Derry, by the Primate of All Ireland, Cardinal Sean Brady in St Patrick's Cathedral in Armagh, last Sunday.
It was a rare double ordination for the Catholic Church in Ireland at a time when the number of young men joining seminaries has plummeted and church attendance is at an all-time low.
"I believe I'm the youngest for a week but there is someone coming after me who will be a little younger," said Father Ryan before the ceremony.
Daunted
Admitting feeling "a little daunted" about the life he was taking on, he insisted he has never doubted his calling.
"I feel in my heart that God has called me . . . I am very happy and excited to be setting out on this new life."
Fr Ryan, who, unusually, went straight from school to St Patrick's College, Maynooth, and spent part of his studies in Rome, is in no doubt about what he can bring to his new role.
"As a young priest I hope to play my small part in bringing new enthusiasm and energy to what is often perceived today as a weary, old institution. The church is alive! The church is young!" he said.
An equally overjoyed Thomas told the Irish Independent he couldn't wait to begin his new life.
"I just want to go out there and share the Gospel of Jesus Christ because that is why God called me to be a priest. I know it is going to be challenging but I am really excited," he said.
The two young men embraced warmly to loud applause at the conclusion of the moving Ordination Rite in the cathedral.
Dr Brady told the hundreds who were assembled that the recent Eucharistic Congress had shown people's "huge thirst to know God".
"There were hundreds who couldn't get into lectures and workshops because there wasn't enough space," he said.
He added that the youth of the newly ordained priests made them perfectly suited to helping young adults to grow spiritually.