A long answer is better than a short one. A long answer will give you time to reflect, contemplate, and make the change more permanent.
Normally I think about the direction my life is going, what the future may hold. In the meditation I did this morning however, my thoughts moved to focus on my higher self and how to become her.
I imagine myself in nature. Either walking around or sitting still. My 'happy place' that I go to often is a lake I enjoy going to near my house. Surrounded by a thick forest. Get really into the details like the smell, sounds and the way the light shines through the trees, if its breezy etc. There's good guided meditations for this too!