aw nothing. its just really really hard work.
at first year its like yeh this is great I <3 doin this... but as you get further along in the course you get so overwhelmed by everything you gotta know, the responsibility, the work, the stress.
i went through this phase, but u soon get over it and u learn to love it again.
if u really wanna do it, go for it. but a lot of people drop out in first year cos its not what they expected - they think its easy cos of the uai.