You Set the Terms

Exactly how to be a sponsor is up to you and the person making the pledge. Just talk about it. Do they want to hear from you once a month?  Six months from now? Do you want to set up a reward? You and your pledge-maker can decide in advance how much of a hard-ass you want to be, anything from easy-going right up to Larry David.

A Friendly Nudge

If your pledge-maker is enjoying the changes in their lifestyle, point them towards further actions.  If they enjoy their visit to a vegan restaurant, ask them to go again. If they like cycling to the grocery store, ask them to try cycling to work and back.

A Pledge Circle

If you know lots of people making pledges, a pledge circle is a great option.  You can meet for lunch or dinner, start a book club, whatever you like.  Be social, talk about the benefits and challenges of the changes you are making, enjoy the small pleasures in life.