While I think having a "Thankfulness Walk" is a great idea, it may be more than you can put together at this time. Another way you can focus on being thankful - a simpler way - would be to ask your volunteers to email you something they are personally thankful for. Then, each week in your weekly communication, you could include the thing one person is thankful for so everyone can thank God together! This is simpler and keeps your focus on being thankful all year!
This is just another way you can be intentional about thanking God for His many blessings. What do you do to intentionally thank God?