Queen reigning for 70 years due to her 'mental discipline': Report

Queen Elizabeth's mental discipline helps with her job role at 95, says royal expert.

Speaking to PEOPLE, Ingrid Seward said that "her ability to compartmentalise has been extremely helpful in her life," as she juggles family with her public role.

Ingrid added: "Fundamentally she puts things in a box and says 'that can be dealt with on Thursday,' for example. She won't let things crowd in on her. She is mentally disciplined and that has helped her through these 70 years.

"It has enabled her to deal with all the things and not allow things to overwhelm her. It goes a long way towards explaining her ability to be able to still be working at this age," concluded Ingrid.

The royal biographer's statements come amid Queen's difficult year post-death of husband Prince Philip.

The Queen also spent a night in the hospital for preliminary tests in October.