Wear loose , comfortable clothes. Layers are good as you can take off a layer as you start to warm up or add a layer as you cool down. Wear appropriate shoes or trainers.
Check the pollen count and pollution levels before you exercise outdoors. You can get daily information from the Met Office – air quality and Met Office – pollen count. If pollution or pollen levels are high avoid exercise outdoors.
Use warm up and cool down before your main exercise. By warming up your heart rate will gradually increase and you will breathe more quickly and deeply. The warm up involves stretching all the muscle groups and warming up your muscles by increasing blood flow. Marching on the spot for 2 to 3 minutes, knee lifts for 30 seconds, 10 knee bends to a crouching position, shoulder shrugs and heel stretches. See an example: NHS Choices – How to warm up before exercising.
Cool down is also important to allow your heart rate and breathing to return to your resting level.