FROM Monday to Saturday, private water aerobics trainer Shirley Cornelius practically lives in her swimsuit and swimming cap.
When the morning sun starts blazing down, she whips out her sunshades and slaps on sunscreen before starting her aqua aerobics lesson.
Says the 31-year-old, who has been teaching aqua aerobics for the past eight years: "I love being outdoors and interacting with others, so this job suits me fine."
During classes, her exercise routine is usually accompanied by invigorating music and, sometimes, her jokes. She gives her instructions with so much zest that her students say she "yells" at them.
"My job is to get people interested and comfortable exercising in water, especially when they are doing it for the first time.
"They wouldn't know what to expect and may have their doubts as to whether they can get a proper workout from water aerobics," says Ms Cornelius, who obtained an aqua aerobics instructor certificate from FISAF, an Australian fitness institution in Singapore.
Most of the time, her students reap enough benefits from the workout to continue with the class.
A former fitness trainer, Ms Cornelius also occasionally uses aqua aerobics to rehabilitate people with neck or back injuries.
Ms Cornelius' speciality is deep-water aerobic exercise, where participants work out in water at least 1.8m deep with the help of a floatation belt strapped around the waist.
About the benefits of aqua aerobics, she says: "The best part about exercising in water is that it acts as a cushion, and deep-water exercises create no impact on the joints.
"So, no matter how hard you work out, there is no pressure. Plus, working out in the water keeps us cool in our tropical climate."
The majority of her students are housewives, young working adults, retirees and pregnant women.
She conducts both individual and group classes. The group size ranges from five to 15 students each time, depending on the size of the pool.
She starts each one-hour session with warm-up exercises. They are followed by more vigorous moves like leg kicks, running, stomach exercises and push-ups by the side of the pool.
When teaching a class of old-timers, Ms Cornelius typically stays on land from where she gives her instructions.
When there are new students, she demonstrates the exercises first on land, then in the pool.
Sometimes, she incorporates props - such as ankle weights, foam dumbbells and noodles (long foam tubes) - to add more resistance to the workout.
Occasionally, she does research on the Internet for new moves and techniques and tries them out herself before introducing them to her class.
Suitable for all
Like every fitness instructor, she is certified in first-aid and cardiopulmonary resuscitation.
So far, she has not had to rescue anyone, although she has encountered students who suffered from leg cramps.
She says: "There are bound to be people with different levels of fitness and injuries, so I try to do a general set of exercises.
"And when I have pregnant students, I give them a different set of exercises and caution them not to work out too intensely.
"You need not know how to swim, as most of the moves are usually done with the head above water. It may look easy, but once you're in the water, it's a hell of a workout, and it's a great fat-and-calorie-burning session!"
In her years of teaching aqua aerobics, her most memorable experience comes from training non-swimmers.
She says: "They find themselves so comfortable exercising in the water that they forget they can't swim.
"Also, on many occasions, those with chronic back problems feel their pain easing after a few sessions of deep-water aerobics, and they wonder why nobody had ever told them about such an amazing workout!"