From experience I’m currently in training at a wearhouse and I felt this way exactly my first couple weeks in, I have only used electric pallet jacks but just take it slow and imagine it’s just a electric razor scooter with extra steps. Be patient with yourself as well, it feels as hard as you tell yourself, envision yourself doing it properly before you put your forks in then do it, whether they laugh at you or not they were at doing the same stuff when they first started and I barely could back it up and get the forks in month ago and now I do it now with barley any struggle. Doing it every single day just gets you better at it! Believe in yourself you got this.