The point of a 21-day challenge of this sort is to help develop a habit or attitude that will make a positive difference in your life. One way I've found that helps reinforce my attitude for gratitude is to keep a gratitude journal in which I note and reflect on those things for which I am grateful. Another habit I practise occurs at the end of the day before I go to sleep. I reflect on my day and identify 3 acts of kindness or people for which I am grateful. I find that I fall asleep much easier with such positive thoughts in my mind.
And upon waking I will reflect on 3 positive aspects of myself or loved ones for which I'm grateful. That helps get me off to a great start to the day. Try it. What do you have to lose?
Have a great-ful day!