〜ものだ

年を取ると疲れやすくなるものです。

Toshi o toru to tsukareyasuku naru mono desu.

One does tire more easily with age.

ものだ states a general truth — that is simply how things are

昔はよく叱られたものです。

Mukashi wa yoku shikarareta mono desu.

I used to get told off a lot.

On a past form it becomes reminiscence, tinged with feeling

人の話は最後まで聞くものだ。

Hito no hanashi wa saigo made kiku mono da.

You hear a person out.

It can also become the tone of instructing a junior