While 35 - 40 feet may be all you need on many Trout waters, it will likely fall short for many other species and waters. I'd watch you tube for a while and learn to double haul. One thing I have discovered works well for many people, myself included, is to practice making the motions in front of your computor while you watch it. You don't even need the rod in your hand. Once you get the double haul figured out you should be able to hit between 60 and 80 feet pretty easily. If you do like my friend Bill who is a freak of nature, you will one day be able to break the 130' mark with a 5 wt. He learned it almost entirely by watching the videos he found on line. That and a rediculous amount of practice. This is a video that shows the double haul and learning the way I just mentioned;
Here is a guy who is seriously good at it. If your neck is still in good enough shape to watch your back cast and you want to get seriously far casts, watch your backcast. I can't remember how far he cast a three weight, but it was well over 100'. You should just work on busting the 60' mark for now.