Yong Boh Sern was born in 1915 in Pingtan, Foochow (now Fuzhou). She migrated from China to Malaya with her mother and son after her husband passed away. She then married Ling Mook Siew, also a Chinese migrant and widower with a daughter and son, through an arranged marriage. 

Boh Sern and Mook Siew had five sons, the eldest of whom was born in 1933, and a daughter named Ai Hiong, their youngest child who was born in 1944. They settled in Kampong China, a small village in Sitiawan, Perak, where they built a wooden house for their family of 12. Boh Sern, Mook Siew and Boh Sern’s mother were converts of well-known evangelist Dr John Sung.

Boh Sern loved God and spent many hours praying, sometimes aloud, reading the Bible and singing choruses and hymns in between. One day, when Ai Hiong was about five, she went to her mother's room to look for her. The room door was closed but when Ai Hiong put her ear to the door she could hear her mother talking to someone. Curious, she pushed the door open slightly to see who was visiting. There was no one with her mother who was kneeling by her bed and talking to someone. “Who are you talking to, mother?” Ai Hiong asked. Boh Sern waved to her and invited her to kneel beside her. There, on their knees, Boh Sern taught Ai Hiong how to pray. 

Boh Sern served in the church as a “Bible woman” (equivalent to a lay preacher today). Their home church was the Chin Hock Methodist Church in Kampong China, Sitiawan. Reverend Lim Swee Beng was the pastor. As a Bible woman, Boh Sern worked alongside Reverend Lim, helping to teach Sunday school and organising Bible study for women and young people. Occasionally, when the pastor was out of town, Boh Sern would preach at the Sunday service. She also teamed up with the pastor to do home visitation, visiting members from home to home to sing, pray and read the Bible with the families. 

Every month, one family would open their home for a home service and they would invite their neighbours and friends to attend. Again, there would be singing, prayer and testimonies and the pastor would speak. The meetings were always edifying and glory was always given to God.

Boh Sern’s ministry extended beyond the local church to other small villages where there were no churches. Her best friend, Madam Lu Hong Keow, worked alongside her. They would ride their bicycles, going from house to house to invite people to attend the meetings which were usually held in homes. About 20 people would attend, sometimes more. Ai Hiong would always follow her mother to all the meetings as she was the “baby” of the family and there was no one to look after her at home. She would sit with the children on the floor. Madam Lu would pray and Boh Sern, who had a beautiful soprano voice, would lead the singing and tell Bible stories using a flannel graph which the children thoroughly enjoyed. 

After a while, these meetings became more regular and attendance grew. Not long after, a building was purchased and it became a local church with a full-time pastor. Boh Sern and Madam Lu moved to other nearby villages and started new churches. More people came to believe in Jesus and were baptised. The churches grew in number and God's name continued to be glorified. 

Boh Sern and Madam Lu also visited Pangkor Island, a small fishing village off the mainland of peninsular Malaya. They would take a bus to Lumut, about 16km from Kampong China, and board a small boat to the island, a trip which took 40 minutes. Madam Lu later bought Ai Hiong a small accordion to accompany the singing and she became part of the team. These meetings were good missionary training for Ai Hiong who later attended Bible college and became a Christian education worker. 

At the beginning, they had no meeting place so they met under the shade of a huge tree. When the children heard the music from the accordion, they would come running and their mothers would follow. Soon, they had a small group meeting under the tree. They sang, prayed and told Bible stories and Boh Sern shared the gospel. One day, one of the women offered to open her home for their meetings and they met there for a while until a building was acquired. Many believed in Jesus and were baptised.

Both Boh Sern and Madam Lu were part of a band of Bible women in Sitiawan. Madam Lu was a prayer warrior who was much loved by the Ling family. Her son, Moses Tay, was an international tennis champion and became a history teacher and later headmaster of the Anglo-Chinese School in Sitiawan. Tay’s wife, Ho Ung Ging, who was also Ai Hiong’s primary school teacher, would later become a prayer partner and “sheltering tree” for Ai Hiong during her mother’s illness. 

Boh Sern was also a good cook and seamstress. She sewed for the American missionary women who were serving in the school and churches, and would use the cloth remnants to sew a blouse or skirt for Ai Hiong. When Boh Sern preached in church occasionally, Mook Siew would tease her by saying, “I guess I have to sit there and listen to my wife preach to me again!”

Mook Siew was always supportive of whatever Boh Sern did and when she was busy with her preaching and evangelistic work, Mook Siew held the fort at home. He was a simple, kind, honest and hardworking man. No job was too menial for him to support his family. He reared chickens, ducks and pigs, planted vegetables on the land behind the house, helped the fishermen in Pangkor Island part-time, and sold snacks. Mook Siew also learned to dress wounds and was nicknamed “the dress-wound man”. He would carry a first aid metal box on his bicycle with cotton wool, bandage, scissors, tape, creams and lotions. When people could not afford a doctor, they would see him and he would dress their wounds.

In 1965, Boh Sern was diagnosed with third stage cervical cancer and given one year to live. She needed weekly radium treatment in Kuala Lumpur and it was a difficult time for devoted husband Mook Siew and Ai Hiong who were the main carers. Following her recovery after her treatment, Boh Sern continued her preaching and visitation ministry for another four years before suffering a relapse. She was called to eternal life on June 29, 1969, aged 54 years. 

The many people at the funeral was a celebration of her life. The 99 girls of the Girls’ Brigade, whom Ai Hiong was captain of, stood as guard of honour for a woman who was a good role model and lived a respectable and fulfilled life as she carried out the Great Commission in Matthew 28: 19-20 of “going and making disciples of all nations, baptising them in the name of the Father, and of the Son and of the Holy Spirit, and teaching them to obey everything” that God had commanded her.

Mook Siew passed away 14 years later on August 24, 1983.