You don't weight train because you're really not sure what to do. You don't want to hurt something, or worse yet, look dumb at the gym. You feel a little self conscious about your ability to yell and grunt with the guys camping out at the dumbbells.
Okay, fair enough. Too bad. For you, I mean. You're just a girl and probably can't handle it anyway, so never mind.
Oh what's that? Why bother? Okay then, here's why:
1. If you're afraid that weight training will make your legs or anything else too big, may I first suggest that you re-evaluate your ideals. Beauty is in the eye of the beholder, but who really beholds stringy wafes? Maybe it's the modeling "experts" or other women, but it's certainly not men. I've never seen a girl get huge and mannish by adding a few resistance moves per week.
When you're an adult, it's good to look like a fit adult and not worry about how much you weighed at 18. Muscle is the reason for "toned." It turns you into an all day calorie burning furnace and you can actually eat without gaining fat. Using resistance to "tell" your body it needs muscle truly is the only solution to the "skinny fat" look that inevitably occurs if you make good on your commitments to diet hard and do cardio. It has to do with some hormonal adjustments that your body makes during chronic stress and calorie deprivation, but the main point is that it turns into a losing battle where the best scenario is you as the female version of Jarrod (Subway).
If you have trouble keeping unhealthy weight off, don't pull the genetics card unless you've given strength training, moderate cardio, and moderate calorie restriction at least 6 months to a year. Please no warp speed extreme fat loss when what you need is consistant non extreme changes over many days. And if you have successfully managed to stay rail thin, don't tell me it's not miserable. The salads and hunger pangs don't get old? The drawn out cardio isn't a time drain?
What's that? You like long cardio or maybe you run (or would like to try running) competitively? Okay then.
2. While I'm tempted to hit runners with the threat that they must do some strength training or else be injured, the truth probably lies somewhere between "or else" and "just go ahead and listen to your heart; do as much as you want of whatever you love."
As noted here in the Gospel of Not Running, jogging may take more of a toll on the joints than other activities where maximal muscle activation lessens the strain. Did I mention that muscle is functional for opening, carrying, and kicking all kinds of things. Some studies have shown that the addition of a minimal amount of strength training does carry over to a competitive advantage in endurance events.
Walking is low impact, but the next logical step for those with greater fitness aspirations is not jogging. Speed walking is a safe option and scores you lots of points for salsa hip action, but most of you should try intervals of some variety plus a few circuits of total body strength training.
3. Ladies - make your own claim to real strength training! There's plenty to do at home with the most basic gear. At the gym, go at the dumbbells with confidence. Not lycra unitard confident, but the kind of confident that trumps everything: working hard and looking like you know what you're doing.
Real training is not laying on your back to pound out one rep on the bench press in between circuits of flexing in the mirror, talking fantasy football. While I'm aware of at least one study that proved grunting to be slightly beneficial in weightlifting performance (yes, people publish peer-reviewed research on this), I'm pretty sure you can get all the physiological benefits without yelling around like a meat head.
Pilates and yoga and Zoomba are not my thing to speak on. While I'm sure they are good, I'm also sure they are not the all encompassing thing for women's health that they're often promoted to be. Just like the guy who can bench press a house but can hardly walk stairs without being winded, many yoga people suffer the consequences of spinal hypermobility. Many Pilates people could stand to get up on their feet and brace their core hard while they lift something (relatively) heavy from the floor.
The point of this writing is not to offer specific suggestions on a 5-step workout plan, but to help you rethink weight training and possibly consider changing things up a bit...without being too long winded.