Clear, informative, and persuasive communications can significantly boost the success of your event by focusing participant attention on the 5 keys to behavior change (awareness, knowledge, resources, capacity, and motivation).
Here are a few things to consider:
Choosing Your Communication Outlets - which of these does your audience use?
Internal communication/posting spaces
Communication Guidelines - how do you want to express your challenge to them?
Aim for positive, aspirational language because this is exponentially more motivating than negative, avoidance-based messages.
Audiences enjoy and respond more strongly to thinking about the ideal/desired end result of their actions more than to a picture of failure.
Loss aversion can be useful, but aspiration is even more powerful.
Communication Timing and Content Outline
14 days before the event
7 days before the event
2 days before the event
3 days after the event start [events at least 7 days long]
7 days after event start [events at least 10 days long]
14 days after the event start and every 7 days afterward [events at least 21 days long]
2 days before the end of the event [events at least 7 days long]