Martha Kearney meets Kathy Willis, Professor of Biodiversity at Oxford University, at Kathy's local stamping ground of Port Meadow, the protected common land in the heart of Oxford, to hear about how her love of the natural world has shaped her life.

Growing up in London, Kathy has always been someone who spends a lot of time outdoors - whether in city parks, rural campsites or cycle trips abroad. Her mother instilled in her a deep respect for nature, teaching her the local names of plants from a young age. Kathy shares how she carried on this passion into her degree, and later PhD in palaeobotany at Cambridge. She's since researched how ecosystems help protect us from climate change and floods, and more recently has been exploring the relationship between nature and health in her book, Good Nature.

Kathy chats with Martha about the scientific evidence about why interacting with nature really does make you feel better, from sight, smell, sound and the hidden sense - your microbiome. They wander around this special, wintery meadow close to where Kathy lives, with its glorious open views stretching into the distance, and reflect on the myriad of benefits it brings to both humans and wildlife.

Producer: Eliza Lomas

Martin Clunes is best known for his roles in the long-running TV series Doc Martin and the 1990s sitcom Men Behaving Badly. He's also known as an animal lover, but few people are aware of the wider importance of nature for him. In this programme Martha Kearney travels to his Dorset farm to meet Martin and find out more about his love of the natural world. She learns of the sanctuary it provides for him from the hectic life of an actor. Together they take his five dogs for a walk, including the retired guide dog Martin gave a home to after hearing about her on a radio programme. He introduces Martha to his horses, as he prepares one of them for a show the next day, chatting to her while on his hands and knees shampoo-ing the horse's fetlocks. He explains how horses were the reason why he came to buy a farm by chance.

Producer: Emma Campbell

Martha Kearney meets much-loved cook and writer Delia Smith for a winter walk around her garden in Suffolk. She speaks of her lifelong love of nature, and her deep concerns for the environment in the face of climate change. She tells Martha about her childhood growing up in the Greater London suburb of Bexleyheath, climbing trees and digging up vegetables in her Grandfather's allotment. Then, in the early days of marriage, Delia and her husband Michael decided to leave London for a tiny hamlet in the country, where they have lived ever since. At the bottom of the garden is a field that Michael bought her as a surprise birthday present, which they have now turned into a wildflower meadow with a duck pond at the centre. Even in winter, the place is a hive of activity. Delia gives Martha a tour of the pond, past a memorial tree with special significance, and into her treehouse where she wrote many of her best-selling cook books. Their walk winds up in her kitchen garden, where the sprouts are growing in time for Christmas, and where the winter herbs are soon to be picked to make stuffing.

Producer: Becky Ripley