Michelle Obama has opened up about her fitness regime and asked other women to share how they 'take care' of themselves in a gym selfie.

On Sunday, the former First Lady wrote: 'It doesn’t always feel good in the moment.'

'But after the fact, I’m always glad I hit the gym. How did you all take care of yourself on this #SelfCareSunday?,' the 55-year-old mom of two added.

The former First Lady can be seen dressed in gym gear, holding a heavy ball over her head in a weighted lunge.

The former First Lady can be seen doing weighted lunges while holding a heavy ball over her head

Obama has become increasingly focused on spreading a message of wellness to other women. This photo from her Instagram shared that she would sometimes hold fitness classes with some of her girlfriends at bootcamp weekends at the White House

She has become increasingly focused on spreading a wellness message which began with one of her chief campaigns as First Lady during Barack's presidency.

'Let's Move!' started in 2010 and sought to stem the high rates of childhood obesity in the United States.

The mission for the campaign was 'solving the challenge of childhood obesity within a generation so that children born today will reach adulthood at a healthy weight.'

Former US President Barack Obama and First Lady Michelle Obama participate in the unveiling of their official portraits during a ceremony at the Smithsonian's National Portrait Gallery

'One of the reasons I took on the issue of wellness is because we’re dealing with an obesity epidemic that is shortening kids’ lives. I started with kids because my hope was that we can do for our kids when we can’t find the time to do for ourselves,' Obama said during a televised interview with CBS Anchor Gayle King at Essence Festival.

'Starting with young people was a way to ease into the conversation.'

During the interview in July this year, she also emphasized the importance for women to look after their health and referred to her father's early death as a reason for her own self-care.

According to People, Obama has said she is a fan of yoga as it keeps her flexible.

'One of the reasons I took on the issue of wellness is because we’re dealing with an obesity epidemic that is shortening kids’ lives,' Obama said during a televised interview with CBS Anchor Gayle King at Essence Festival.

During the interview in July this year, she also emphasized the importance for women to look after their health and referred to her father's early death as a reason for her own self-care

'When it comes to our health as women, we are so busy giving and doing for others that we almost feel guilty to take that time out for ourselves,' she said.

'If we don’t have our act together as women, as mothers, as grandmothers, we aren’t going to be able to get our kids on track.'

Instagram users were delighted at the motivational post.

One said: 'She is really out here with abs!'

While another complemented the First Lady's appearance: 'That's what a woman should look like, nothing fake and inflated!'

'She is really out here with abs!,' said another.