Some of my favorites when I'm eating really well are- non-fat plain (not flavored) yogurt sweetened with an equal with fruit or granola mixed in; egg whites on wheat toast; They sell egg whites in cartons like milk so their easy to use. Apple slices with PB; and balance bars in the chocolate/pb gold flavor for easy on the go snacks.
Walking will do something if you do it consistently, but you have to be moving at a good pace. When I walk I work up a sweat and couldn't really gab with a gf the whole time, too out of breath for that. Also, my neighborhood has a lot of hills so if I jog I will jog UP the hills so its harder. Your body gets used to what you do daily, that is why what you do at work doesn't make any changes and why you should change your exercise routine regularly. Interval training is a good way to kickstart things too- jog one minute, walk two minutes... repeat. Workout videos are a great way to vary things, but I've never done them. Totally not coordinated enough for that! lol