Aparigraha consists of non-accumulation, which can manifest in very subtle ways.

As long as our happiness relies even partially on having things, we will never be free, we will always depend on them to be happy. Only when we give up our attachment to things will we be able to be truly free.

It is quite common to experience an almost imperceptible form of fear of not having enough, which can be manifested in different forms of accumulation such as overeating, overspending, holding on to things for years without ever using them, etc. That fear can happen because we fail to see the abundance of life, and trust the universe to bring us what we need. 

Abuse of the world's resources can be another consequence of this. Using more water than we need to, using the car for most things when we could consider other options, consuming too much electricity just because we like to have lots of lights on, and so forth.

We can also be inadvertently using things to reinforce our sense of identity. Specific clothes, objects, the car we drive, they can all feel absolutely necessary for our mind to maintain that idea that we've created as who we are. And we can also find ourselves judging others based on those patterns too. And in time it's not about having enough to fulfil our needs or provision for old age, but in indulging in superfluous things that contribute to this identity. 

We can find a subtle resemblance between this Yama and Brahmacharya, but Aparigraha is founded in the control over objectivity, whereas Brahmacharya is more around the control over subjectivity (e.g. the way we relate to things).