Guidebooks tend to go overboard about the health hazards of trekking, particularly altitude sickness. Don’t be put off – the vast majority of trekkers never experience anything worse than a sore throat (common in high, dry air) and a mild headache. That said, trekking can be physically demanding, and may take you a week or more from the nearest medical facilities.
Children, seniors and people with disabilities have all trekked successfully, but a certain fitness level (or, failing that, bloody-mindedness) is required. Don’t allow yourself to be talked into biting off more than you can chew or you’ll have little fun and could get into trouble. It’s certainly worth checking that your insurance policy doesn’t exclude trekking, which may be listed as a hazardous sport. Check the policy on helicopter rescue as well.