TL;DR: Track team agile/scrum changes. Display them on an 'achievements' wall in chronological order. Showcase team wins & experimental process improvements. Aim for quantity over quality. Use to increase team motivation and external stakeholder expectations.
“A team is not a group of people who work together. A team is a group of people who trust each other.” — Simon Sinek
Teams are akin to living organisms that shape, change and react to events as they grow, learn and consume. When teams face a challenge, the positive events in the past can be forgotten during times of conflict, hardship or a looming large challenge.
Showing the team's past achievements openly in the office to bring about pride in the team's accomplishments and a sense of connection through shared team triumphs. Using simple bullet points and tracking week by week the changes the team has made and the projects/team achievements that were completed.
- Teams need shared experiences to unite around
- Linking Cause and Effect of new process changes to create an environment for safe experimentation
- Leaders are expected to bring chnage 
Boost Morale: Strengthen the Team by showcasing Changes & Achievements
.... or why leaders can encourage change by tracking change
During the last 10 years of my career I've been in different leadership positions, some as a senior developer of a small team and others as a ScrumMaster, Product Owner or Agile Lead.
I've always tracked the weekly incremental changes that the team has introduced to then be able to reflect on which changes made the largest impact. Some of these changes are as simple as introducing Scrum Retros or as small as setting a percentage of the team velocity for 'tech debt'.
This 'tracking' started as a personal activity -- but ended up being incredibly useful tool for not only motivating the team but also doing internal team marketing to other stakeholders in the company.
"Leaders have Followers. Managers have employees. Managers make Widgets. Leaders make Change" - Seth Godin
How to do it?
Write down 1-2 changes that the team introduced or important events that happened on the Friday of each week.
It's useful to track positive events that happened (new hires) and also events that have strong value for the business (increased velocity).
Example Change Tracking List
- First team retro introduced
- moved from Trello to Jira
- started cross functional code reviews
- all tickets groomed & story pointed in sprint
- TEAM WIN: new UI designer hired
- 'technical support' point of contact rotata introduced
- first sprint velocity calculated
- introduced Kanban for technical support
- introduced 'code freezing'
- TEAM WIN: single-signon feature live!
- weekly scrum of scrums introduced for external teams
- TEAM WIN: velocity increased!
Don't over think, keep it simple
Start off with a simple text file -- after a couple of weeks, print it out and stick it on a wall.
Why do it?
- Leaders are expected to bring in change 
- Actively encourages the agile culture of safe experimentation
- Useful to encourage other teams to experiment
- Useful for learning what changed worked (with some relatively)
- Useful to show how 'mature' the team is becoming
- Useful for training others to become ScrumMasters/Agile Leaders
- Useful for helping other teams outside your team to optimise
- Useful for internal team marketing for stakeholders
- Useful for your career beyond ScrumMaster and into Agile Leader
- Increase Trust amongst the team based on past performance