To have positive energy doesn't mean that all of your days are absolutely good. It doesn't mean that bad stuff doesn't happen to you. It's more about how you handle the bad stuff. It means that you find the good in the day and you live based off of that. And once you find a way to start living like that everyday you will exude positivity.
To conclude, when we say we are sending strength and happiness to someone else, I find that to be absolutely true. Not just a figure of speech. It's something that we all posses the power to do. So keep your energy positive and your spirits high because it won't only change your life but also others around you.