TNT courses are usually offered during summer, fall, and winter months (winter at our retreat center); however, participants could still be faced with challenging weather conditions including storms, high winds, varying temperatures, intense sunlight and insects. Physical demands on the applicant may include carrying a backpack weighing upwards of 40 pounds over uneven terrain, ascending and descending steep surfaces, and/or canoeing in rivers with strong currents. Elevations for some courses range from sea level to 10,000 feet. On backcountry treks, participants sleep outdoors in tents and protected shelters and will spend most days hiking, backpacking and/or canoeing. They set up their own camp and prepare their own meals. Because some TNT participants may be immuno-compromised, appropriate water purification methods (e.g., boiling, filters) are used to prevent cryptosporidium.