Tours in Bhutan are rated as an easy to moderate tours. Most of our tour we would undertake in Bhutan is a completely based on drive with car except few hikes to hill side monastery (Tiger nest). Except trekking, tours of Bhutan involving cities of Paro, Thimpu, Punakha & Gyantey, peoples do not really required any high Himalayan tour/ trekking experiences. Most of our tours are below 3000m from sea level thus altitude is not an issue usually. Peoples of any age and fitness can easily plan tour in Bhutan without any problem however pre-planning and pre exercise is always appreciated.
But if you preparing to undertake trekking trip in Bhutan, you should be very much prepared as according to the nature of trekking (Primary, Intermediate or Advance).