One of the most successful and rewarding things that I've achieved in my fitness career is teaching complete beginners and non exercisers into a more healthy, active lifestyle and to become regular exercisers. I didn't set out to do this, it just happened. The thing is, I didn't become a regular exerciser myself untill my early to mid forty's, so I can emphasise with anyone just starting out. I know how daunting and worrying it can be to join an established group or class not knowing anything, what to expect, or how you're going to feel. Especially when the rest of the class or group just breeze through everything, chatting away, whilst you're maybe struggling just to breath and feeling awful. Some personal training sessions are well worth considering at this stage. A routine and program, which will serve to stimulate and motivate you, can then be prescribed to cater for your personal circumstances, abilities and goals.
There's one mistake, that virtually every beginner makes and is probably the main reason why people give up. That one mistake is the most simplest, easiest thing to avoid and the reason why so many people that train with me become lifelong exercisers, because with me you don't make that mistake.