The most common fear I've encountered not only as a health coach, but as someone who has been surrounded by people interested in health and fitness for years, is the fear of becoming "bulky." Many women, specifically, have a goal of becoming "toned" but won't do the exercises or the workouts necessary to achieve that goal because their fear of becoming muscular or appearing masculine outweighs their ambition for their goals.
Becoming "bulky" (for lack of better words) isn't nearly as simple as many act. There isn't a woman on Earth who accidentally became bulky. If you meet a girl in the gym and she fits your definition of bulky, it's because she wanted to be. It's because it was one of her goals, and it's because she trained with the right intensity and ate the right foods for so long to achieve that goal.
The definition of bulky to many women seems to be someone who is not only muscular, but lean enough for their muscles to be apparent to others. Toned, on the other hand, seems to be a reduction of body fat and what, a slight appearance of muscles? The difference between the two, besides the fact that one is sought after and the other is feared, is the extent---the difference is how muscular and how big someone appears to be, both of which are subjective.
As a result, becoming "toned" is a stepping stone to becoming bulky. It's something one would achieve before being considered bulky. So why not strive to be bulky and stop short of it? Why not strive to go bigger and farther than your actual goals, and then maintain once you achieve your goals? If your goal was to have $1,000 in your savings account, why wouldn't you work hard enough to have $10,000, and then stop once you achieve your original goal?
The point is, no one has ever achieved that level of fitness by accident. In fact, no one (at least that I know of) has ever said they got "too fit." So, my advice to you is to go for bigger. Push yourself like you are going to the Olympics, or like you are training for a show, because no one achieves their goals with anything less than maximal effort.