Inspiration to go to the gym?

im 17 female and have just joined gym but im intimidated by loads of very big men and i have went from 1 hour a day to 1 hour a week. im tryin to watch films which include females working out, u know like in terminator 1 or 2 i think it is. any tips for motivation anyways? its really important as i need to get down to a size 6 (uk) for my modelling contract and im currently an 8 UK. thank u :) xx