no need for supplements or any expensive way of motivation (maybe something to listen to because gym music sucks)
just walk in there thinking "this is not a place to impress or show off how much i can lift its a place to get 6-12 reps in each set and get some GAINS" and dont worry about asking for help either, it might make someones day to help someone out with their gains
this strategy worked for me when approaching my first gym experience
one more thing: walk into a gym with one goal and that goal is to walk out on your own 2 feet (dont hurt yourself)
The gym is a great place!
There are so many people to help you.
All those mean people with their game face on are soft and fuzzy on the inside.
Not many people judge and are very open to questions/spotting/help in general.
Just get your butt out and go. Force yourself just to get there for a few days and then you'll be raring to go.