First of all, in order to cast for distance you need to understand and cast well at short range. As others have said, get a good book and videos. Even better, take a lesson from a qualified, not necesarilly from a FFF instructor though, teacher.
Once bad habbits are learned it is very difficult to break em. You mentioned stillwater, that is one area in trout fishing where distance is a big help. However, in stream and even river fishing more fish will be caught with short, accurate casts. That is true even on the big rivers here in Montana. As a guide one of the most challenging situations I face is someone who can cast 50 to 60 feet and thinks they need to out of a drift boat.
Even wade fishing the bigger rivers, short, accurate casts will be more productive most of the time. Having said that, learning to cast longer will improve all your casts. Also, do not try to compare your distance with a fly rod to guys chucking hardware, or bait, with spinning rods. They are two totally different things.
Learn the proper techniques, then practice. It is better to practice away from the water so you will focus on the casting, not the fishing.