So i am a 14 year old male and i am almost 100 pounds (i have a fast metabolism and i eat right) i want to get more fit for when i go to high-school next year i don't have many exercise things in my house but i do have a treadmill. i am running between 6-8 mph for 1 mile. I do have 5,3,1 pound weights that i do sit-ups with (they are too light to lift and get muscle haha!) What else can i do with the things i have and are found in most houses to get fit?