In 2011, which was his final year at St Kevin's College in inner-eastern Melbourne, he was part of his school's successful football, cricket and tennis teams.
Toohey was also a high achiever in the classroom, finishing as dux of St Kevin's after gaining outstanding results in his year 12 subjects: English, maths methods, biology, legal studies, physical education and texts and traditions.
Toohey was subsequently honoured in the Premier's VCE Awards, which recognise the top academic performers in Victoria.
"I was 17 at the time, so I didn't go out a lot, and I just studied and played sport," he told AFL.com.au.
"It was a great year, but it was very hectic. I wouldn't want to relive it."
Last year Toohey began a science degree at Melbourne University and played 20 games in the TAC Cup with the Oakleigh Chargers.
A 197cm, 96kg key-position prospect, he returned to the Chargers this year as an over-age player, adding another achievement to his list by winning the club's best and fairest.
Now, thanks to the Cats' decision to pounce on him with their first pick (No.15) in Wednesday's rookie draft, Toohey has been given the opportunity to make the grade at the highest level in his favourite sport.
"I really wasn't expecting to get picked up at all, so it's pretty crazy," he said. "I just screamed when I found out. I was overawed, really, for a good half an hour.
"I've calmed down now and it's all sunk in, so it's all good."
Toohey's journey to Geelong has included many twists and turns. Having grown up in Sydney, he spent a year of his primary schooling in Canada.
"My parents, being both teachers, did a house swap with a family in Canada when I was 10," Toohey explained.
"To go from 40-degree weather here minus 30 over there, where you had days off school because there was so much snow that you couldn't get out of your house, was the most awesome experience and something I will always treasure."
Toohey didn't start playing Australian Rules until his family settled in Melbourne in 2005.
That year he began attending St Kevin's College (the same school that his new coach, Chris Scott, went to), starting out in grade six.
Towards the end of his schooling, Toohey was mentored by Tom Purcell, who teaches economics, texts and traditions and religion, and is also involved in the football program.
"James is a very determined and focused young man," Purcell told Fairfax Media in 2012. "His academic success was a great achievement and due to his incredible work ethic.
"He also has very supportive parents ... and he has the appreciation to make the best of opportunities presented to him."
"Despite James' success, he is very humble. More impressive is his generosity of spirit to others. He is an inspiration to those who know him."
Toohey will put his studies on the backburner during the early stages of his new career as a full-time footballer.
"I spoke to the club and they just want me to take a year off to get myself right with footy, and then we'll worry about balancing things up," he said.
"I've only got one year of my science degree to go, so I'm in no rush to make study a big part of my life again."
The 19-year-old hit the track with Geelong's younger players the day after being drafted, and his first impression of the club was very positive.
"It's been awesome so far," Toohey said. "Everyone's really welcoming. It's been a great experience.
"I got a call from Joel Selwood straight after I got picked up. He has really extended himself out to the all the first-years, so that's been really great."
Twitter: @AFL_AdamMcNicol