New to ketogenic diet, advice and tips to be successful?

Have tried the south beach diet many times and have been somewhat successful, but hard to stick with. I have been on keto for a week now and have lost about 4 pounds , which I believe is mostly water weight? I am currently 152 and 5"5 My goal weight is 130 (125 would be even better)

I'm uncertain about things you're allowed to eat; for example, soy products and legumes ? I see recipes that have these items but have been told to stay clear of these items ?

I also am trying to stay active and workout about 5 times a week but have felt more lethargic lately. Is working out a necessity to put your body in ketosis ? Or what kind of activity should I concentrate on? Cardio, circuit training, or weights ?