Multi-Tasking Skills Off-ice Quick, Explosive Starts POSTURE is the  #1 skating fundamental
Nothing wrong with most traditional exercises in the weight room, of course ...
... they are one small piece of the puzzle, and you must add hockey-specific workouts as the summer progresses.
Learn skills ... the Russian way
Hockey is not played in a barrel,   so ...
Thinking outside the barrel ??? Build or Purchase Slide board,
Russian box, or PlyoTubes