Originally Posted by BassYakker
This could be due to a number of different things. My best recommendation to you is to have a buddy watch you fish and give you pointers on your casting, or even have someone film you while you cast. If you don't look like you are casting effortlessly, there is either something wrong in your technique or your outfit may be unbalanced (leader too long, flies too heavy, etc.) Are you false casting a lot?
My first gut response would be to go up to a 6wt and let the rod do the work, force yourself not to "power" your casts. I am a believer that you actually use less effort with higher weight rods.
Hope this helps and good luck.
Phil