Sources of Potassium

So, according to MFP and based on gym instructors & yoga teachers, if one is very active and sweating a lot during the day due to physical activity - then potassium must be replenished and good amount of it must be consumed during the day.

Per my MFP, I need to consume 3,500 during the day - and I usually just get it from banana and coconut water (which I had too much of today.) Does anybody know of another GREAT source of potassium? What is the best to serve it too?

Would truly appreciate your inputs on this. Thanks!