"I was just done with excuses, done waiting for people to 'give me time' to work out. I decided I'd had enough and if I wanted to live a long and happy and strong life with my boys, I was going to have to prioritise myself too."
Within four months she managed to lose 15kg, an achievement she is enormously proud of.
"Who would have thought I'd get in the best shape of my life at 35 and with 3 kids in tow?" Ms Klizs wrote on Instagram.
"I still have stretch marks on my hips, I have a wrinkly saggy belly button, my chest has shrunk down to nothing but I kind of like it all and the transformation feels sweeter because I know what my body has been though carrying and feeding three babies."
"I only had one goal in February when I started all this. It was to be strong and feel happy," she wrote.
"I love that today I can say 'yes' when my seven-year-old asks me to walk them both to school because I know I have the lung capacity to run to both schools and come home again. I love that I can say "yes" when my 25kg three-year-old asks me to pick him up because he's tired of walking. I love that I can carry my baby around and still cook dinner without hurting my back.
"I love that I can breathe normally again, that my stomach isn't constantly hurting me and that I have the energy to get through a day with three boys and not collapse on the couch the second they're in bed.
"I love that I decided I was as important as my husband and children are and that I also matter. Because for better or worse, right now I'm kind of the glue that holds this family together and makes the wheels spin on a daily basis."
Ms Klizs, who has a lifestyle blog called BluebirdKisses decided not to follow a tradition "diet" as in the past she has found they're unsustainable. Instead she decided to adhere to the 90/10 rule: Ninety per cent healthy food and 10 perfect food she loves, healthy or otherwise.
"I didn't cut carbs; I replaced white bread with whole grains. I replaced white processed sugar with maple syrup. I replaced butter with olive oil. I forced myself to eat one giant salad a day … every single day," she explained.
Whenever she goes out for dinner with friends or her partner, she makes sure she orders a "giant" salad first, with olive oil and vinegar on the side so she can mix her own dressing.
"By eating that first, I found I wasn't as hungry for the cheeseburger I was going to eat next, so I would naturally portion control it," she explained to Popsugar.
Prior to having children, Ms Klizs ran marathons and half-marathons, so she has started to introduce running back into her weekly routine.
"I started running in my 20s after finding myself overweight from years of residence food and lack of activity," she wrote on her blog.
She credits Aussie Kayla Itsines' Bikini Body Guide (BBG) with getting her in shape.
"I'm on week 18 of BBG, four weeks of @kayla_itsines beginner program and 14 weeks of BBG 1.0 and 2.0," she explained on Instagram.
"It's part of my life now. But the biggest change is the mindset. Through the experience I realised I'm happy with me and I think I'm setting a good example for the kids too."
She does three resistance days a week, 28 minutes each, at home. She also runs three to four days a week, alone, with a stroller, with her dog, or all of the above.
She says she uses the @sweat app "religiously".
"I love that I can incorporate the runs I love with the strength training I need and it's all super flexible and I can do it from home every day. It's quite literally changed my life more than just changed my body."
Ms Klizs advice for anyone wanting to lose weight is "the most important thing is to do it for yourself".
"Don't do it for the scale; don't look at it with a singular goal in mind. Look at this as a marathon. Take the steps you need to get to the end and don't worry about the time it takes. Before you know it, you'll find a new lifestyle, a new energy, and I promise it's worth it."
