Though some treks venture near glaciers, and even cross the foot of them, most treks do not allow the fulfilment of any Himalayan mountaineering ambitions. Nepal's mountaineering regulations allow trekkers to climb 18 specified peaks with a minimum of formality, but you must still make a few advance arrangements for such climbs. Many agents offer so-called climbing treks which include the ascent of one of these peaks as a feature of the trek. There are a few peaks that, under ideal conditions, are within the resources of individual trekkers. A climb can be arranged in Kathmandu if conditions are right, but a climb of one of the more difficult peaks should be planned well in advance.
A Trek Requires Physical Effort
A trek is physically demanding because of its length and the almost unbelievable changes in elevation. During the 300-km trek from Jiri to Everest base camp and return, for example, the trail gains and loses more than 9000 metres of elevation during many steep ascents and descents. On most treks, the daily gain is less than 800 metres in about 15 km, though ascents of as much as 1200 metres are possible on some days. You can always take plenty of time during the day to cover this distance, so the physical exertion, though quite strenuous at times, is not sustained. You also can stop frequently and take plenty of time for rest.
Probably the only physical problem that may make a trek impossible is a history of knee problems on descents. In Nepal the descents are long, steep and unrelenting. There is hardly a level stretch of trail in the entire country. If you are an experienced walker and often hike 15 km a day with a pack, a trek should prove no difficulty. You will be pleasantly surprised at how easy the hiking can be if you only carry a light backpack and do not have to worry about meal preparation.
Previous experience in hiking and living outdoors is, however, helpful as you make plans for your trek. The first night of a month-long trip is too late to discover that you do not like to sleep in a sleeping bag. Mountaineering experience is not necessary, but you must enjoy walking.