It's good that you had this knee jerk reaction to embarrassment, but it won't sustain you come two weeks time when our tired and feeling lazy (trust me I know). Whilst you've already made the first step, you have to actively want to change because you want to improve yourself for you and you only. To often I see people say I wish I was this or that, news flash people your the only person stopping yourself from being that.
If you really want to loose weight I would highly recommend a gym and potentially a trainer. Weight training has the added bonus of continuing to burn calories after you've finished working out. The trainer will help you with keeping workouts fresh, showing you do's and don'ts, most likely help you a lot with nutrition who his surprisingly important (if it's not right don't bother) and most importantly will keep you accountable so you for fall off the wagon.
If you really want to change, then go out and do it.......simple as that.