A Way of Increasing Stamina?

So I'm not expecting miraculous results immediately, but I would appreciate ways that do it quickly and efficiently and allows you to retain your stamina level even if you pause doing it for a while. Also if it's something you can do on a daily basis. I'm trying out for high school basketball next year, so I want to spend this year training. If anyone has methods, whether you do them yourself or know from other people, any answers would be greatly appreciated. Thanks.