There is no reason to fret about exercising.  Take "baby steps" to get into a gym at your house or a near by gym.  And push yourself while you are there  to improve on your strength and ability.  Your body is only as strong as you make it.  Knowing yourself and what you want for yourself can drastically change your mind, body and spirit.  Don't get overwhelmed.  Change does not occur overnight, so you must relax and give your body proper rest in order for you muscles to recoup.