How to use 'used to'

There are two ways of using 'used to' depending on what follows it.

If 'used to' is followed by a noun or noun phrase, it means 'accustomed to'. For example, the sentence 'I am used to sleeping late at night' means 'I am accustomed to sleeping late at night'.

On the other hand, 'used to' means 'in the past I did something habitually'. The following sentence illustrates this point:
I used to run around the field 30 times daily when I was young.
(=In the past, that is, when I was young, running 30 times around the field every day was my habit.)