Provide the theme summaries for the following conversation: 

Rob: I wanna start Get off the couch challenge! Who's with me? I'm gonna start with 30 min of activity every day.
Greg: way ahead of you mate! at least 60 min a day!
Rob: good for you! 30 min a day is gonna be challenging for me!
Greg: good luck then!
Will: don't be too hard on yourself. better to be realistic. fingers crossed!
Anna: i'm in! 30 min sounds reasonable! 
Greg: look for variety of exercises such as walking, biking, swimming whatever you enjoy!
Anna: i'm gonna need lots of support from you guys!

Summary: 
Rob wants to start doing 30 minutes of physical activity every day. Greg is already doing 60 minutes. Anna wants to start exercising just like Rob. 