She already seems ready for the challenge. Only last year, she won the US National Association of Intercollegiate Athletes (NAIA) title, finishing a 3km indoor race in a record time of 14 minutes, 12.05 seconds.
She has competed in Asian events, juggling training with her studies at Lindenwood University in the US. With the help of her British coach Paul Wright, she has moved ever closer to her Olympic dream.
Surprisingly, though, Ching wasn't always interested in athletics. As a secondary student at TWGHs Mrs Wu York Yu Memorial College, "I wasn't really what you'd call 'sporty' at school. I was in the choir and didn't like sports", she says.
Yet when she started hiking as an activity in Form Six, Ching's teachers immediately spotted her talent.
"They said I was a speedy walker - even faster than some of the boys," she said. "One day they told me they had entered me for the 2007 junior female category of the MTR Hong Kong Race Walking event. I didn't know what race walking was, but I took part." She did so well on her debut, she won the bronze medal.
Encouraged by the success, she began formal training under her first coach Bill Purves, a Canadian based in Hong Kong. "I joined his club Sahn Hahng Tai Bo and I did quite well in competitions. Bill encouraged me to improve my race walking ... to get a scholarship [at a US university]," says Jessica.
Sure enough, she was offered a grant by Wright at Lindenwood, where she was accepted into a four-year bachelor's degree programme.
Ching took America by storm, beating seasoned athletes to become the national university champion in NAIA indoor race walking last year and in 2010 - the first Hongkonger to win the title.
She also competed in last year's Asian Race Walking Championships in Japan during dramatic times after last March's earthquake and tsunami. She arrived in Tokyo at about 3pm on March 11, missing the huge quake by only an hour. Organisers chose to go ahead with the race - leaving the athletes waiting for eight hours on the aeroplane before sending them on a nine-hour train ride to a domestic airport, from which they flew to the race venue, Nomi City - a trip that usually takes 90 minutes. She and a male teammate ended up missing a full day's training on March 12.
Unbelievably, Ching still finished sixth in the 20km race in 1 hour, 45minutes, 31 seconds - breaking the Hong Kong record. "My coach, Paul, was very happy, but I thought that, if I'd had more rest to recover from jetlag after flying back from the US, I could have been faster."
She will compete in the same event again in March, when she plans to finish in a time of less than 1 hour and 40 minutes.
Her performances impressed Wright so much that he took the job of head coach two years ago at the Hong Kong Sports Institute, where Ching has a placement as she trains for the Olympics.
Despite a tough training schedule, Ching continues to study online. "Since my subject is exercise science, I applied for a placement at the institute [in Hong Kong]. I'll be here for the next six months to focus on training. Then I graduate after the Olympics."
Athletes can compete in the Games if they have enough points (based on their best times in qualifying racers), or if their country selects them. Ching's best time is about 1 hour, 45 minutes - only seven minutes off the Olympic time. She is quietly confident of beating it.
So with her trainers laced up tight and her eyes on London, her dream may just be a heartbeat away.