welcome to the world of bowhunting! id get use to missing a few cuz its gonna happen. I have missed a few myself over the yrs. myself wouldnt take a shot at 40 yds, theres to many things that could go wrong at that distance like wounding an animal etc. Like the others said let em get closer andif they dont just enjoy the moment and wait for nexttime. make sure you follow thru on your shot, dont punch the shot, andI cant give ya any advice on buck fever cuz I havent figured that out yet........LMAO. When I usually set my stand I try to pace off 20 yds and get an idea about where my limits are. I also clear lanes etc. I try to pick 2 or 3 trees to climb up in so that way i can play the wind. Bowhunting is a learning experience and always will be. It took me 7 yrs to bag my first deer with a bow. Calm down and take your time it will happen, dont rush! I wish ya luck this yr