It took me a while to realize that this is one of my secrets, but I have come to realize that give tips when asked, helping a fellow sparkler in the panic board, or in a private message is in turn motivational because it reminds me where I have been and how far I have come. In turn, it motivates me to keep going. I don't want to let myself down.
Every week, choose one SparkFriend to concentrate on. Visit their page every day at least once. Read their blog. Check out their activity feed. Comment on things. Send them goodies. In general, just keep in touch with that friend every day. Pick a different friend every week. You'll not only encourage your friend...you'll encourage yourself along the way. WIN-WIN!!