Nowadays, our lifestyle is less healthy than it was in the past, although there has been progress in medicine.
We lack the time not only to do physical activity, but also to be with our family.
("To do" and "to be" are parallel. That is, they have the same grammatical structure, following "not only" and "but also.")
I have attempted to write in English, but I always encounter difficulties with grammar.
(I prefer to use two subjects, although they are the same. This makes the sentence clearer.)