[Tvita]

Which version is correct and why?

Sen 1:

1) Different people have different understanding of what is rest and how to spend their leisure time.

2) Different people have different understanding of what rest is and how to spend their leisure time.

Sen 2:

1) I think, it is very important for them to rest their minds during leisure time.

2) I think, it is very important for them to rest their mind during leisure time.