From wikipedia:
Meatless Monday is an international campaign that encourages people to not eat meat on Mondays to improve their health and the health of the planet. Meatless Monday focuses its initiative on Mondays for multiple reasons. Monday is typically the beginning of the work week, the day when individuals settle back into their weekly routine. Unhealthy habits that prevailed over the weekend can be forgotten and replaced by positive choices. A weekly reminder to restart healthy habits also encourages success.
NYT reporting that the concept is catching on in some places:
A new nationwide pro-veggie effort, however — aimed at persuading people to go meatless at least one day a week — has been embraced here Aspen) more than in any other city in America. At least 20 institutions and restaurants, including Syzygy, are offering vegetarian choices on Mondays under a plan announced this month.
Why not give this a try today? It is a healthy choice for you and for the earth as well!