I know multiple people who would like to lose weight but when I suggest going for a walk they all make excuses. Yes, people have busy lives but if you wanted it bad enough, you'd spend 20 minutes just walking and chatting with a friend. How else can I approach the situation or at least motivate myself to keep helping them? It has gotten to the point where I don't want to bother asking but at the same time, they continue to complain/vent to me about their weight and so I do want to help.
EDIT: And they have asked me to help before. (i.e. make sure I don't eat too much at the party, or make sure we go on walks this summer, etc.)