The major problem is methodology. Most people have had an initial bad experience in the past. They have done too much. It has been too hard and they have not experienced results quickly enough to continue.
If you want a program that you will stick to, you must start with small steps and realistic expectations. As a personal trainer with 1000 or more client's, one thing still surprises me. Most new clients can't believe that the first session is over. They expect it to be more work and go more slowly. You MUST work at a level that is within your capabilities and only then proceed to a more intense level.
A few tips to the beginner. Don't do the same exercise more than once and don't ever work out hard enough that you can't talk. Variety will keep you from getting bored and a heart monitor will keep you from working too hard.
There are hundreds of exercises. Start a program where most of those exercises are ones that you like (or at least don't hate). I've had clients who were 200 pounds over weight and could do our program. The key is small steps and consistency. You can do it! If you want proof give us a call for a free session.