If you have dreams about the future, it means that you are looking ahead and planning for the future. You are thinking about things you'd like to do, places you'd like to go, etc. Even though you are "old" in years, you are still "young" on the inside. ("young at heart)
If all you have are regrets about the past and no dreams for the future, it suggests that you think your life is pretty much over. You don't see any reason to plan exciting things for the rest of your life. In that sense, you are "old." You have lost your enthusiasm for life.