find some fun ways to motivate the gang. Challenge them to "ride the temperature". We used to make this our annual New Year's Day ride- if it was 12 degrees we'd ride 12 miles. If it was 40 degrees we'd get a decent ride in of 40 miles. (Doesn't really work for celsius and kilometers). Below zero we'd go to a bar and watch a football game.
worst thing to be is judgemental and mocking -they'll just dig their heels in and won't crawl out from under the rock until the crocuses are in bloom.
I don't do much club riding or racing anymore and mostly ride solo but I use the same tactics to get my own lazy butt out the door- I find ways to make it fun and a challenge.