During the Meditation, this is one of the five questions that I ask. And with each different Parami like Generosity, Morality, Renunciation and so on, I ask the question, "How much have you grown?" Some people do find that it's helpful to reflect on examples of how they have grown. That's fine. Some people can get more of a feel for how much.
For me, it was dramatic. Before I was a meditator, I was an okay person, but I wasn't anything special. I didn't consider myself to very compassionate, very loving, growing up. I was just what I thought kind of average. I didn't go out of my way to do any charity work except for one small thing in college which was more for fun than for real thoughts of charity. I never really thought about myself as being somebody like I am today. So when I think of myself today and how much I've helped so many people, I have this feeling of size. My generosity was little before I was a meditator, my generosity is huge now, so I can get this feeling of size but actually it is based on understanding how I've actually been generous. Because if I hadn't done anything generous then I wouldn't have the idea that I am very generous. So the two kind of go together, to actually be able to reflect on how much you've grown in generosity often means you are going to think about how you've actually grown in generosity, too.