Hi Renee

Have you tried Pilates, since your knee is hurt? It's very low impact (you do most of it lying down) and can help re-strengthen your knee, as well as help tone the rest of your body. When I had each of my girls (both by ceserean), Pilates was what I did to get back into shape. I know it's not the same as your problem with your knee, but it's hard to find any excercise you can do if you're injured in any way. Walking is great too, and since your kids are 4 and 5 years old, you may be able to take them with you. I know it's a rough task, I have two of my own (3 years old, and 17 months old, so I get to put at least one in a stroller :P), but it's worth a try. You could also get your husband involved, and make it a family thing. Just an idea

I'm sure you already know how important water is, so I won't go into that
Try green tea, it cleans out your body and gives you energy, without a lot of caffeine. Try eating 5-6 small meals a day, instead of 3 large ones, this will help you keep your energy up throughout the day, and boost your energy ALL day. I would suggest high fiber & protein foods, and not cutting out carbs, but limiting sugars and starches, like white bread, potatos, onions, junk food, soda, etc. It worked for me I hope this helps some, and good luck to you!

Sandra