This is an idea for the whole family to get involved in!
Take a jam or coffee jar and decorate it (I used sparkly paper because I like that type of thing!)
Cut up some bits of paper and put them by the jar with some pens or pencils. Put the jar somewhere accessible to everybody at any time e.g kitchen table. When something good happens or someone has been kind to you, write it on a slip of paper and put it in the jar.
Make a routine of opening the jar once a day or once a week when everyone is together, reading the slips and saying thank you to God for His blessings! Maybe you could even glue them all into a book to look back at in the future to see how God has blessed you!