Thread: which sentence is correct?

which sentence is correct?
каждый день я буду бегать 20 минут
каждый день я буду бежать 20 минут

Kаждый день я буду бегать по 20 минут. - You need the preposition "по" to express distribution (equal amount of time for each day).

You can also get without "по": Kаждый день я буду бегать 20 минут. But with "по" it sounds more natural.

Finally: Каждый день я буду бежать (по) 20 минут. - Can also be possible, but in the following context: you always run in the same direction (imagine, you are running from New York to LA, it's a long way, and you cannot run the whole distance within a single day).