How hard is undergraduate physics?

Well it's not really that difficult, but you just have to work hard. Also, the exercises take much more effort than high school physics. In high school physics (and maths), you're supposed to memorize methods for solving various problems (which usually involves just plugging in numbers into an equation). In undergraduate physics, at least at my university, you're supposed to figure out for yourself how to solve the problem. This is difficult for a lot of people because they aren't used to it.

The best advice I can give is to first get used to self learning. Learn the material beforehand by reading books or watching video lectures by yourself before you go through the material in class. And secondly, have patience. If you've been doing a homework problem for 5 hours and you keep getting the wrong answer, don't get stressed out.

Physics takes twice as many undergrad credits for the major as other majors, sometimes even around three times as many, in addition to the actual material of course being very challenging to learn

Engineering has more job prospects than just a degree in physics.