1. Donate whatever money you want to whatever charity you feel would benefit from that cash. Don't post a video of it, don't throw water on your head. Do NOT- I repeat DO NOT- challenge others to do so. What a person can give to a charity and to what charity they believe is beneficial is none of your concern.
2. I've seen the 'gratitude' challenge. Dude, if you need someone to TELL you to be grateful, you've got problems. Even in my worst days: my worst pain, my most desolate times, there were things to be grateful about. Even if that gratitude was that I woke up alive that day. If you're stuck in a complaint rut, think about 5 good things that happened to you today, even if one is that you got dressed correctly.
My list of gratitude is endless. When you see geese dance like that, it always brings a smile to my face. That's George, by the way...drying off after a bath.
My other challenge to people is to get off their duffs and DO something that they have not done either in a while, or in ever. Say hi to a person on the street. Sit and stare at fluffy clouds... just DO something that involves just yourself and something that makes you smile.