^ What Rie said. The only I think I have cut out is sodas and dairy, but only because I found out I was lactose intolerant. If you would like some variety in your water, try using water and cut up some strawberries and let them soak overnight. You can also do it with lemons and other fruits. It is delicious and adds some flavor to your water. If you have caffeine headaches, I would also recommend green tea. Just don't add tons of sugar to it! I used to go to a ton of Buddhist retreats and all they had was tea and water to drink, and I looooved it.
EDIT: Oh I forgot, it also helps to vary up your exercise routine! Water aerobics, especially in deep water, is great resistance and is very easy on injuries and joint problems. Also, most gyms and yoga centers have a Gentle Yoga option, which is meant to strength and build up muscle without injuring your ankle any further. They focus on restorative poses and it should help a lot! The important thing is to not get stuck in a rut. Add time to your walk or try walking on different terrain, or walk in the woods! Variety will confuse your muscles and keep you losing.