first I wanna say congrats for choosing this awesome path of life. getting to your question, mechanical engineering has considerably doable theoretical course like fluid mechanics, strenghth of materials, thermodynamics and some other kinda challenging courses but it also has courses of more practical applications like CAD, finite element analysis, manufacturing. but the thing you should enphasize here is that mechanical engineering is a very vast major so you should have to specialize in one or may be two related sub fields and master them. what ever route you choose don't expect your UNI or the teachers to teach you everything(in fact they will maybe give you only about 20% of knowledge) there is a whole new world of knowledge and skills out there that you need to figure out by yourself. see the big picture...I mean its easy to graduate with a good grade but the market doesn't just that. you should be an all-rounded but also experienced in some areas(and its not easy but its doable).