As you get older, more and more things become difficult to do.
There are more things that are hard to do as you age.
この場合、次のように言うのが良いかと思います。
ーAs you get older, more and more things become difficult to do.
「年をとるにつれ、ますます多くのことがやるのが難しくなってきた」＝「難しいことが増えてきた」
as you get older で「年をとるにつれ」
more and more で「ますます多くの」
to become difficult で「難しくなる」
ーThere are more things that are hard to do as you age.
「年をとるにつれ、やるのが難しいことがもっとある」＝「難しいことが増えてきた」
as you age で「年をとるにつれ」
ご参考まで！
カナダ 
