If you want to burn a candle, what do you have to do? you have to light it. I once got told from someone that inspires me a lot - "If you want to burn a candle, you first have to light the wick" - obvious, but has other meanings. That applies to getting in shape. You could have the best PT at your beck and call, but if you don't take the first step, nothing will change. If you want to be fitter, look better, feel better, you have to start things off (just like lighting the wick).
It is very common to struggle with taking those first steps - many people say "I would love to look better but I just don't have the motivation". How to help this?
First of all, write down the reasons why you want to get in shape. This could be anything from simply looking better, to a change in career. Then, you want to surround yourself with inspiration - print pictures of physiques you would want to have, and also pictures of your current self - to show where you are and where you want to get too. Everyone seems to be on Facebook and Twitter, so if you are, follow accounts of athletes, personal trainers, nutritionists, fitness models, celebrities that are in shape - so every time you log on, you are bombarded with motivation! This can very easily light that wick and get you on your way to the new you!
As with many things in life, being in shape doesn't just get 'given to you', you have to work for it. Don't sit around and wait for a good body to appear, because it's just not going to happen. Take that first step, and you will thank yourself later!