The idea that less weight tones muscles is wrong. Less weight and more reps builds endurance. For explosive power, do fewer reps with heavier weight. Just remember that to really increase strength the general consensus is that you have to work with at least 60% of your maximum lift (the heaviest weight at which you can complete a singe repetition). Definition is not an issue when deciding how many reps to do and how much weight to lift.

In reality, there is no such thing as lifting for definition. Muscular definition is one thing: muscle mass minus body fat. You cannot lift to make your muscles more defined. To look ripped, you have to shed some fat.

It starts with your diet. You have to eat right. There are many ways to eat right. One thing that works well for almost everyone is to cut out milk and milk by-products (creamers for coffee) from the diet. Also, don't eat any complex carbohydrates after lunch. A perfect dinner might be salad and tuna fish.

In addition to lifting weights, do cardio often. Many people are afraid that they will lose muscle by doing cardio. In reality, doing cardio (in addition to eating well) is the only way to get cut because you have to lose that body fat. The more cut you are, the more jacked you look.

In conclusion, lift weights, eat well, do cardio, and look ripped.