You can prepare mentally by praying, planning to share yourself with others, and committing yourself not only to your own needs, but to the needs of others.
Prepare for physical activity. Brisk walking, jogging, bicycling, swimming, or other activities that increase your heart rate for a sustained period, are best for preparing you. If you have not been too active recently, start slowly and increase the time you spend on these activities. Try to work up to exercising for at least thirty minutes a day, three or more times a week. Make sure your hiking boots are broken in to avoid blisters on the trail. All will help you be better prepared for hiking in the mountains.