My husband and I received a couple's journal as a wedding gift. It's to write little love notes in. The last one to write in it leaves it on the other's nightstand. It's been >11 years and we still use it. It's really useful now that we have little ones. It helps us stop and be grateful for each other amidst all the stresses of parenting.
Start on January 1st with an empty jar. Throughout the year write the good things that happened to you on little pieces of paper. On December 31st, open the jar and read all the amazing things that happened to you that year. Gratitude!!