They are just right for my needs, while working out in the gym. I like that they don'r fall off while rowing or on the Stairmaster.
They come with instructions on fitting your ear and a toll-free customer service phone number. If there are any fit problems they say to call the number and they will walk you through adapting them or send you whatever ear adapters you might need. Basically they guarantee a perfect fit.
The rubber they use is also soft and gummy and not hard plastic like Apple headphones. I really like that. Overall I would recommend them for fitness.
Yet, I'm not a fan of people using these while riding a bike or running trails. Listening to headphones except when using stationary equipment or swimming laps is risky and puts others at potential harm as well. I bike and hike past idiots on the trails all the time who zone out to their tunes and can't hear.