I like to take a simple approach to not only strength training but nutrition, business, and life in general. Don't complicate things. Life if stressful and complicated enough as it is. The last thing you want to do is start to stress about your workouts. "Is 10 the best rep range to hit or should I try for 5?" "Do I need to lift at 90% of max or 85%?" Quit worrying about these little details. Do what works for you. Perhaps even more important, do what you enjoy and will stick with for the long haul. I like to say the best exercise is the one you will actually do!
While I do strongly believe that lifting heavy weights is the best training strategy for both men and women, if it is something that you absolutely despise and much prefer running, then run. Getting out and moving, jumping, lifting, running is far better then sitting inside and watching TV.
For example I absolutely love lifting heavy weights. I cannot even express the joy I get from setting PR's at a squat, deadlift, or military press. Lifting heavy weights challenges my mind, body, and soul. It keeps my joints feeling good (when done properly) and my body feeling powerful. That all being said Kristen doesn't enjoy it nearly as much as I do. The thought of going to the gym full of people just turns her off. If it was the only way to exercise she might not even do it.
What she enjoys is kettle bell (KB) workouts, yoga, and running. Basically anything that can be done outside or even at home. She loves being able to take her kettle bells into the sunshine, the compound movements you can do with them, and how versatile they are. You can get strong, powerful and lean from just using KB's. They are a great tool!
Maybe you like doing body weight exercises or a combination of everything? While certain exercises will have slightly different results, what is important is that no matter what you choose you are always pushing yourself.
Use heavier KB's. Do more reps. Perform a certain workout faster. Change the angle of your push-up's. You get the idea. Always push yourself to improve on the previous workout. Just going through the motions will not only provide minimal results you will almost certainly get bored and quit.
One thing I strongly recommend is to keep a training log. Record your weight, your reps, your time, etc. Then when you preform the same workout next time you know what you need to do in order to make improvements from before.
Maybe you used a 16kg KB for swings. Next time try 20kg. Or maybe try 2 extra rounds of swings. Having a log will not only keep you motivated but it won't leave you guessing on what you need to do to make an improvement.
Remember that the best exercise is the one that you will actually do! Keep things simple. Always push yourself to improve. If you begin training this way you will see some awesome results.