In Europe, there has been a serious decline in physical activity over the past 50 years. Adults aged 20-60 years【C1】______500kcal less energy per day than they did 50 years ago. This is the【C2】______to the running of a marathon each week. Even【C3】______of participation in walking and cycling are declining, all of which suggests we should be【C4】______to the nearest gym. But the "green" policies of these establishments【C5】______to be pretty disappointing: factor in air-conditioning, laundering of towels, energy-consuming exercise【C6】______and the fact that 90% of exercisers【C7】______to the gym. British Military Fitness, the UK's leading【C8】______fitness provider, offers a programme of nationwide classes in parks, and on common lands, in the【C9】______of its Gym Intervention programme. The organisation【C10】______not just the fitness benefits of working out outside, also our need to spend time in the great outdoors to【C11】______overall mental and physical wellbeing. Group activity is declining as fast as our fit ness rates, so the complete ethical workout doesn't merely【C12】______the greenness of the equipment, but also the social capital to be【C13】______by joining in. It also【C14】______to start early. Children urgently need to become more【C15】______. and yet according to Natural England, a public body that encourages people to enjoy their natural surroundings, the amount of time and【C16】______children have with nature is declining; fewer than 10% now play in natural places【C17】______woodlands, countryside and common land compared with 40% of children 40 years ago. Research shows that children who are【C18】______to nature will continue to visit【C19】______landscapes in adulthood and be committed to【C20】______them.