Whoever told you that about walking and running needs some education - look at the olympic serious walkers and runners - they don't have fat legs - it is aerobic exercise - it causes weight loss. Get to work, girl and simply watch potions and eat healthy proteins, non fat dairy, fruits and veggies, whole grians and high fiber grain foods, and use very small amounts of healthy oils for cooking. Even weight training won't bulk you up unless you have a 'tendency" and it would still take dedication and heaby weight s to cause that response.