Kirwan, who features swimming in television commercials for mental health, says in the book that swimming is one of the strategies he uses to cope with stress.
"If I'm feeling a bit under pressure, I know I need to slow down, do one of my relaxation things - go for a swim, play my guitar, have a nice breakfast and really focus on tasting the food. Get together with people I love and do some laughing," he writes.
He said students needed to learn what suited them.
"They taught you English, the finer points of English," he said.
"Why couldn't we do wellness? Why can't we do life's balance? Why can't we teach people that once a day you should be doing something for yourself?"
Mental health is already one of seven "key areas of learning" in the health and physical education curriculum, which is compulsory from the first year of primary school to the end of year 10.
Health Education Association chairman Bernard Butler said all students up to year 10 were expected to have "opportunities to learn around mental health education and wellbeing from a holistic viewpoint".
"It could be through drug education, it could be through [Police programme] Keeping Ourselves Safe, it's around empowering young people with resilience, teaching children an understanding about being resilient," he said.
The Education Ministry's Te Kete Ipurangi website contains teaching resources on four mental health topics: friendships; social skills; change, loss and grief; and "making connections", a topic aiming specifically to build social connections and resilience for students in the first two years of high school.
But Lynfield College health education head Kathryn Wells said the curriculum did not specify how much time schools should devote to the whole area of health education, and in practice it varied widely.
"In some schools they may have maybe 10 classes in the whole year. In others they may have a lot more," she said.
At Lynfield, students have health classes once a week in year 9 and twice a week in years 10 and 11. Lynfield makes it compulsory until the end of year 11, one year later than the curriculum requires.
"It's really, really important for students to understand, recognise and know how they can overcome various things, and also to know that it's normal to have difficult times," she said.
"We need to have time. The thing about health lessons is that we need to build a really supportive environment in order to have those kinds of conversations with students.
"If you are not given time to build those relationships, you are already on the back foot and the students are not going to feel comfortable talking about various things."
WHERE TO GET HELP
• Lifeline: 0800 543 354 (available 24/7)
• Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• Youth services: (06) 3555 906
• Youthline: 0800 376 633
• Kidsline: 0800 543 754 (4pm to 6pm weekdays)
• Whatsup: 0800 942 8787 (1pm to 11pm)
• The Word
• Depression helpline: 0800 111 757 (available 24/7)
• Rainbow Youth: (09) 376 4155
• CASPER Suicide Prevention
If it is an emergency and you feel like you or someone else is at risk, call 111.
