is it tht hard to work hard?

Yes. After a while, you get burned out.

An old boss told me, "Don't work hard. Work smart."
It doesn't matter how much effort you put into things. People only look at the results.
Nobody cares how much time and energy you spent doing something. They only care about getting the job done.
Sometimes, working hard doesn't mean you'll get what you want. For a lot of people, that counts as an automatic failure. You missed the goal; you failed.

Not for those who work hard. But it very hard for those who only thinks about it.

"Don't give up, the beginning is always hardest."

In the beggining yes. But eventually it will become your normal. Then others will admire you for working hard when to you its just your regular pace.

No. you should be raised that it's a habit.

I’ve never found it so. But admittedly it’s easier to work hard at something you enjoy or that at least has a purpose you can appreciate.

Depends upon the purpose in hand.