Yes, you do put smiles on people's faces!!
(They may not write back always, but they smile!

)
DON'T believe what mother and father have told you, when it has been negative and not really constructive!!
My parents like to criticise too, then they FORGET about it!!
That's their idea of 'inspiring' people, yikes!!
If they're anything like mine, they think by criticising they will make you go from 'okay-ish' to 'great/brilliant' and then they can brag about you!! (They will, if you accomplish anything, even if they don't say it to your face!!)
You work and you study, what more can someone expect from someone your age??
(If they do, well, probably their expectations may be unrealistic?)
Maybe they want you to help out around the house more too or something? People can be very cranky when in reality they may just be lonely and/or miserable etc.
It's a difficult economic climate and parents/older people may get a tendency to 'freak out'...
My mum told me if I don't get good grades, I'd be working in a wood factory... I did get good grades and later on there were suggestions to go work in the factory anyway!!
Every work is honorable, nothing wrong with working in a restaurant or such either! (You might own one or a few in a few years/decades too?!) (Okay, legs can hurt and you might get varicosis, a friend did, which isn't nice - so maybe studying and passing those exams is better?

)
Many people, who were successful later on, had only average, some even below-average grades!!
If you don't have that important other things to do, might as well study?

(And then show success, so they won't know what to say?)
hm, could you get a good scholarship/internship if your grades improve?