1
I don’t do many exercise because I don’t have many time.
I don’t do much exercise because I don’t have much time.
Use many + plural countable noun: ‘many books’, ‘many people’.
Use much + uncountable noun: ‘much exercise’, ‘much time’.
2
I saw many films last year.
I saw a lot of films last year.
We normally use many in questions and negative sentences: ‘Did you see many films?’ ‘I didn’t see many films.’
In affirmative sentences, a lot of is usually more natural in everyday English. The purple sentence is grammatically correct, but it sounds more formal.
We also use many after too, so, as and how: ‘There are too many people.’ ‘She has so many books.’
Check our grammar lesson on much, many and a lot of.