Miss Liew Wei Yong is a personal trainer and fitness manager with local gym Absolute Living.
And the hardest step for both trainer and client is the dreaded weigh-in.
The tanned, lanky woman said with a wry smile: "At first, they will deny eating unhealthily.
"But when I get them to stand at the weighing scale, they start confessing to me what they ate a few days before. This can range from durians to curry fishhead, to chocolates and cakes!"
So the 31-year-old trainer's sessions often become life lessons for her clients: How to eat properly, how to train the right way and how to balance work stress.
In the process, sometimes, deep secrets are revealed and she becomes a therapist instead.
The reasons behind her clients' binge eating can range from emotional scars, to stress at work, to relationship issues, Miss Liew revealed.
Women are among her most challenging clients.
She said: "It is common for women to starve themselves hoping to get into a size-zero outfit. Not all of us are born with naturally slender frames!
"With this group of clients, I focus on education - like how unsustainable diets can lead to yo-yo weight gains! So I help them plan a more nutritious diet plan."
Women are also the most critical of their own bodies.
"They have specific areas that they want to work on. Some want to get rid of the abdominal bulge when they sit down.
"Others do not want to show off flabby arms when they wave goodbye to their children - they just want to be the hottest mums in their kids' school," Miss Liew shared.
She has also seen her fair share of crazy clients who set seriously unrealistic fitness goals. Like how a very underweight female client who insisted that she needed to be even skinnier. And the beefcakes who are obsessed with gaining more muscle mass.
"Some of them can be so obsessive in pursuing the look and size that they want, they risk hurting their bodies in the process," Miss Liew revealed.
Then there are the clients who "cheat" while doing the exercises. "What to do? I just give them more sets to do."
She believes in setting a good example for her clients and being extremely fit.
"You can't have an overweight trainer telling you how to lose weight!"
This can be tough at times because she confesses to being a true-blue Singaporean who loves her share of "good" food.
Her favourite food includes chilli crab, chicken rice, mee siam, hamburgers and potato chips. But whenever she indulges, she trains twice as hard to shed the extra calories.
"I mentally count the fat content of the food before I eat," confessed Miss Liew, works out five times a week on her own.
She does a 10km or 25km run, or a 500m swim every day. She also lifts weights in the gym.
An ultra-marathoner, Miss Liew has completed the 250km stage race over seven days in the Gobi Desert in China in 2008. Last year, she attempted the 250km race in the Sahara Desert. But one client almost had her stumped.
They were training for the client's upcoming marathon.
And the gruelling route took them from Claymore Road, past Botanic Gardens, right up to Sixth Avenue before turning back via Dempsey Hill.
But Miss Liew was feeling a little off that day.
"As her personal trainer, I was supposed to set the pace and motivate her along the way. But I was falling behind, so I had to push for all I was worth," she revealed.
At the end of the run, the client said to her "it was a tough run".
And Miss Liew had wanted so much to tell her "it was even tougher for me!"
This article was first published in The New Paper.