Deiting and exercising

Hiy guys, i want to lose some weight and build up some strength in my back again (i have a painful back especially in the cold). I was just wondering what sort of diet and exercise worked for some of you? I have begun to do yoga and Add some apostrophes 😉 30 day challenges, i have a fairly balenced diet. I am however a student at university though :') any advice would be greatly appreciated.