Endurance training is particularly time intensive, so it is most easily incorporated into walks themselves. The following exercises will help improve your overall cardiovascular fitness.
Gym-based training
Being more intensive, even 20-30 minutes of cardiovascular exercise will be of benefit
If you have limited time, use small quantities of resistance to increase effort to balance out your sessions. Carry a rucksack on shorter walks, find gentle hills or walk on soft sand: all can increase the cardiovascular effort.
Jogging, running and cycling can also be included in general cardiovascular workouts. Being more intensive, even 20-30 minutes of these exercises will be of benefit.
Training for long distances
Training for longer distances is about improving your body's cardiovascular system (heart and lungs) so that it can supply fuel to your muscles more efficiently and for longer periods of time. Long distance walking also requires conditioning, to become accustomed to the additional strains and stresses placed upon your body, such as the repetitive movement of walking for long periods or simply becoming used to the weight of carrying a rucksack.
Becoming accustomed to carrying a rucksack © Remains
Initially, do not use resistance on any of the exercises. This will allow your body to become conditioned to the longer workouts you need for endurance training. Endurance training is most effectively done at around 60-70% of your maximum heart rate - as a rule of thumb, this equates to the sort of pace you could hold a conversation at. Unlike training to increase your speed or strength, endurance training tends to feel easy, but it does demand motivation to maintain each exercise for the longer duration.
Treadmills and bicycles - For cardiovascular training, you could aim to build up the duration of each exercise to at least 30-45 minutes.
Step machine - Aim for an exercise duration of at least 30 minutes. Reduce your tempo so that you can maintain a constant rhythm throughout the exercise.
If you have limited time, use small quantities of resistance to increase effort to balance out your sessions
Outdoors-based training
Being outdoors will help avoid monotony, which can occur with indoor endurance training. Vary the terrain and, as you progress, include some steeper hills to balance and maintain strength.