I've lost about 20 pounds so far with sensible diet and exercise, bur I'm stuck around 131 pounds (my goal is 122). how do I jump start my weight loss again?

when you plateau like that, you have to switch up that exercise routine, whether it be making them longer, switching up what exercises you're doing (i.e. if jogging, switching to bicycling and swimming), or add in muscle toning if you don't have that yet. if you have muscle toning routines, amp 'em up, make them more difficult for you. you're body isn't being challenge any more, switch it up, make it a challenge again.