If you take regular walking weekends and are happy covering 16-22km (10-14 miles) each day, with a number of ascents and descents, you will comfortably finish the trek. If you have a sedentary lifestyle and go on short walks once a month you will need to get much fitter in advance. During a typical day on the TMB you should expect to walk for between 6 and 8 hours and be outdoors for 8 or 9 hours. Most of the ascents and descents are not steep, but on 5 days you will climb and descend 1000m.
Age should not be a barrier in any way. Previous clients have ranged in age from 14 to 76 years old. In our experience, the least prepared and unfit are men aged 40-50 years who work in offices.