The Princess Royal celebrates her 60th birthday on Sunday.
She will spend the day with her husband, Vice-Admiral Tim Laurence.
Princess Anne says she will not curb her busy lifestyle, having attended more than 600 engagements last year.
The princess is on the organising committee for London's 2012 Olympics.
She has been president of the Save the Children Fund since 1970 and is president or patron of 320 organisations in total.
She has two children from her first marriage to Mark Phillips; Zara, 29, and Peter, 32, whose Canadian wife Autumn is expected to give birth in December.
However, in an interview with the BBC's Inside Sport programme, the princess played down suggestions that she might take her work down a gear once she becomes a grandmother.
"Look around at the members of my family who are considerably older than me and tell me whether you think they have set an example which suggests that I might - unlikely," she said.
In 1976, Princess Anne, then 26, represented her country at the Olympics in Montreal as a member of the three-day event team.
She was in Singapore nearly 30 years later as part of the team which successfully bid for the Olympics in London in 2012.