Lentils are used in a lot of Indian cuisine, vegetarian dishes, and can be used as a base for a soup. There are plenty of recipes online. I usually just cook it with a bit of garlic, onion, and lemon juice. It goes good as a side dish. You could roast some chicken and potatoes with a side of lentils. It’s pretty good when you mix it with rice. Lentils with scrambled eggs makes a solid porridge-like breakfast option. You could try mixing it with oats or grits too…lots of options!
Cardio probably isn’t necessary, but high intensity cardio like sprinting can be beneficial