21 Day Challenge - I found out about this from a guy's vlog on YouTube (nerimon is his username). You put on a bracelet that you can take off easily, and for the next 21 days, you have to try your hardest not to complain about anything. If you do, then you have to put the bracelet on the other hand and start the 21 days over. Why 21 days, you ask? Well, it takes 21 days to ditch a habit-- in this case, complaining. By the way, it's not actually called the 21 Days Challenge, I just made that up. I can't remember if it actually had a name or not, so I just made up my own. Feel free to use it, though. ;)
30 Day Letter Challenge - This one I saw on the front page of Mibba. Someone was writing a story with it. At least, I think it was a story... Anyway, to do this, you have to write a letter (you don't have to send it) to someone different each day for 30 days. The people for each day are these:
Day 1 — Your Best Friend
Day 2 — Your Crush
Day 3 — Your Parents
Day 4 — Your Sibling (or closest relative)
Day 5 — Your Dreams
Day 6 — A Stranger
Day 7 — Your Ex-boyfriend/girlfriend/love/crush
Day 8 — Your Favorite Internet Friend
Day 9 — Someone you wish you could meet
Day 10 — Someone you don't talk to as much as you'd like to
Day 11 — A deceased person you wish you could talk to
Day 12 — The person you hate most/caused you a lot of pain
Day 13 — Someone you wish could forgive you
Day 14 — Someone you’ve drifted away from
Day 15 — The person you miss the most
Day 16 — Someone that’s not in your state/country
Day 17 — Someone from your childhood
Day 18 — The person that you wish you could be
Day 19 — Someone that pesters your mind—good or bad
Day 20 — The one that broke your heart the hardest/worst
Day 21 — Someone you judged by their first impression
Day 22 — Someone you want to give a second chance to
Day 23 — The last person you kissed
Day 24 — The person that gave you your favorite memory
Day 25 — The person you know that is going through the worst of times
Day 26 — The last person you made a pinky promise to
Day 27 — The friendliest person you knew for only one day
Day 28 — Someone that changed your life
Day 29 — The person that you want tell everything to, but too afraid to
Day 30 — Your reflection in the mirror