Resolved questions
What are the following in Hindi?

I deserve to get a good mark.
mujhe achhe marks milne chahiye, main iske layak hoon.(not word to word translation)
main achchhe marks deserve karta/karti hoon.

They don't deserve to work here.
we yahaan kaam karne ke yogya nahin hain
unhein yahan kaam karne 'ka koi adhikaar'/'ke paatra nahin hain'/ nahin hai.

or simply (strictly colloquial)
ve yahaan kaam karna deserve nahin karte.

What's the purpose of life.
jeevan ka kya matlab hai. Jeevan ka kya uddeshya hai

I need to exercise.
mujhe abhyas karne ki zaroorat hai.(in acadamics, like solving problems of maths)

mujhe kasarat ( means workout here) karne ki zaroorat hai.

or simply (strctly colloquial)
mujhe exercise karne ki zaroorat hai.

He exercises everyday.
wah har din abhyaas/kasarat/exercise karta hai