I agree with Cassie. When I first started walking it was hard. When it started getting easier I walked a little farther and then a little farther. You will know when your ready to make your walks longer your body will tell you. Keep going your doing great
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~Renee~
51 year old (5'4")
Highest weight 234 (9 years ago)
Starting Weight 185.8 (4/10/12)
First Goal 160 (7/10/12) 
161.2
Second Goal 155 (8/31/12)
Current Weight 139.2 (4/24/13)
New goal - lose weight slowly, build muscle & lower body fat
"There is no diet that will do what eating healthy does. Skip the diet. Just eat healthy"