Hitting a target at 100 yards with a bow is not so difficult as you think. Try it. Not only does long-range practice make shots at hunting ranges seem like gimmes; it also magnifies subtle mistakes in shooting form.
If you mess up your form at 30, you may still be in the kill zone. If you mess up at 100, you'll miss the whole damn target and lose a $12 arrow. This forces you to bear down and shoot well.
Week One: 20-40 yards
At these ranges, concentrate on perfecting the fundamentals of good form.
Reread Rules 8, 9, and 12 and apply them while shooting three arrows at 20 yards. Step out to 30, and do it again. Now go to 40, take a deep breath, remember the rules, and shoot five arrows. Relax and shoot five more. Do this whole routine two or three times a day.
With your stance, anchor point, and grip perfected, shoot at 50, 60, and 70 yards, focusing on two things: (A) pushing and pulling through the shot; and (B) floating the pin as you squeeze the trigger.
Week Four: 70-90 yards
Way out here, it's especially critical to push and pull through the shot and to make asmooth release.
Same routine, but at 70, 80, and 90. On the last day, replace the block target with a good-size buck target, step back to 100, and double-lung the thing.