Good for with trying to lose some weight and get in shape. You're lucky you have a trail - if its safe to walk alone then go for a 45 min walk as if you're late for an appt and alternate with biking too. Weights are a fast way to get muscle definition. Ask your parents to buy you the Insanity Workout - its by far the best workout I've ever done. Its hard but you'll start to feel stronger in 3 days.

Don't skip meals since this actually slows down the metabolism. Eliminate unhealthy snacks and look at the fat content of snacks. Fiber 1 has good cereal bars and Special K also has low cal bars. You can treat yourself to baked chips if you're a chip eater. Avoid spending hours just sitting at the computer - this is the 1st time in history young people are so out of shape. Eat fruits /vegetable and cut down on the bread a little. Have pre-cut veggies in the fridge and if you need a dipping sauce, use lower fat dressing or none at all. When eating cereal pay attention to the serving size. Best of luck.