How do you monitor your data usage?

How do you monitor your data usage?: Having come from an era where mobile data usage was once unlimited, it can be a rough transition from the lax world of unlimited data to the hardships of having to deal with data caps with overages or severe throttling. I remember a time when I would stream music to my phones for hours upon hours every day, watch video after video and download anything and everything that interested me, regardless of size. Now, unless I cling to any open Wi-Fi network available, I constantly have to be...