My daughter told me I should start going to the gym. At 79, I'm in the best shape of my life.

• At almost 71, Joan MacDonald was overweight and suffered from high blood pressure and kidney issues.
• The mom-of-three despaired that she might die soon.
• Then her daughter, Michelle, a fitness trainer, told her that she needed to start working out.

This story is based on a conversation with Joan MacDonald, 79, a former driving examiner of Collingwood, Ontario. It has been edited for length and clarity.

January 2017 was a New Year I'll never forget. It was one of the few times that my daughter, Michelle MacDonald, lost her cool with me.

She'd moved to Mexico the previous month and was visiting. "I won't get to see you as often as I like," she said. "And, every time I leave, I won't know whether it will be the last time I see you."

Then she made another blunt comment that changed my life. "Mom, why don't you go to the gym?" she said.

I needed to improve my health

I had high blood pressure, kidney problems, and was at least 70 pounds overweight. Approaching my 71st birthday that March, I felt scared and miserable.

My doctor had already warned me that, if I didn't make an effort to improve my health, I would end up on dialysis before very long. I was effectively dying.

Growing up in Canada, I'd been an active child. I played ball, skated in the winter, and went bowling. I enjoyed doing them because they were fun. But I was by no means an athlete.

I got married a month before my 21st birthday and settled into married life while working as a driving examiner. I juggled work with motherhood, raising Michelle and her older and younger brothers.

Going to the gym really wasn't a thing back then. None of my married friends worked out, or even thought about doing so.

I took medication for high blood pressure

I believe that your body changes every seven years or so. I went through variations in terms of shape and size, and enjoyed certain foods, then went off them.

I didn't have regular meals, often eating just two meals a day at irregular times. In between, I'd snack.

Throughout my 60s, I was in poor health. I'd get bronchitis in the fall and spring — I had weaker lungs after contracting rheumatic fever as a child — and the kidney issues began.

The weight had grown to 200 pounds, which was far too heavy for my height of 5 feet 3 inches. And my blood pressure was high; I was put on medication.

I'm lucky because Michelle is a certified strength and conditioning specialist and sports nutrition coach. She saw how unhealthy I'd become and was worried, especially because she'd moved thousands of miles away and couldn't keep an eye on me.

Her recommendation struck home. It was enough to jolt me into action. My doctor also encouraged me to lose weight and reduce my blood pressure.

I'd half-heartedly attended the gym before, but not consistently. This time, I went five times a week.

My body slimmed down

I sought advice from Michelle and studied YouTube videos to learn how to use the machines and do strength training with free weights. At first, I couldn't believe how hard it was to pick up 20 pounds.

I began with small weights and increased them by increments. I've since done a deadlift of 170 pounds and a hip thrust of 230 pounds.

It was amazing to see my body slim down and fit into clothes, like jeans, that I hadn't worn in a very long time.

I lost 45 pounds in six months and a further 25 pounds during the rest of my 70s. I've gone from a size XL to a medium. I was able to quit my medications.

My current regimen involves spending two hours at the gym, with around 15 minutes of cardio, followed by using weights. I often work out with Michelle, whom I joined in Mexico for around a year after my husband died.

As for my diet, I eat five small meals a day, including oatmeal with egg whites, protein powder, and 1% coconut milk for breakfast.

Then I'll have yogurt, an egg white omelette with ground beef, chicken, turkey, and ham, a protein bar, and a final, plain meal without starches. If I start my day at 7 am, I'll stop eating by 7 pm.

A shoulder injury hasn't stopped me

Unfortunately, I suffered a shoulder injury while biking outside on a rough surface and needed surgery three months ago. I've had to take things a bit easier as I recover. However, I feel 100% happier and healthier than I did before going to the gym.

Michelle and I established "Train With Joan" to help inspire people to take up exercise, regardless of their age.

It may slow you down a bit, but I've seen many seniors, even older than me, accomplish great things. They have resolved to do it for themselves. Nobody else is living in your body but you.