So you’d like to get into better shape but perhaps you’re finding it a bit daunting or are concerned with whether you’ll stick with it. If it’s been a while since you’ve done serious (as in, enough to get you sweating and feeling sore afterwards) physical activity , then start off easy. Your body will need to readjust to the motions and intensity. By starting off slow, you minimize the shock factor. If you happen to start off intensely, then your whole body will be utterly sore and things will be very painful. This on its own isn’t a bad thing (assuming no injuries occur from such a drastic change) but you might be less inclined to continue with the training. Now of course this doesn’t mean take it so easy that you don’t break a sweat. You should be pushing it enough to be sweating and feel sore later on. A workout, after all, requires work, though hopefully it’s something you enjoy (or come to enjoy over time, which often happens). Over time, you should ramp up the physical activity as your body (and your attitude if need be) will get used to the change.