NextGen: Goldie's Guide
Goldie has an over-active imagination, and can sometimes get confused by her hallucinations; not being able to figure out if something is real or not, and sometimes not being able to see something right in front of her. There were many times as a child where she'd walk into a door or wall when she saw fields or clouds.
As she got older, she was able to control her imagination (to an extent), and know whether or not something was real or her mind. But as a foal, she couldn't do this easily. Her parents at one time got her glasses thinking it was her eye sight, but help from Discord and Candlewick revealed it was the hallucinations; distracting her from the path ahead. There wasn't much they could do about this, so Goldie adapted and started holding onto pony's tails and following them. Most of her friends didn't like having their tails in her mouth, especially Candlewick seeing how his tail isn't like pony tails, and since Goldie tends to bite down on the tails she grabs… Eventually only Apple Spice was "okay" with her biting her tail, because to an Apple; family means everything. It became a sort of routine for them, they even got so insync to eachother's movements that they could confidently run together.
As Goldie got older she didn't need to grab Spice's tail as much, but she still does when they run because she doesn't want to run the chance of running into a tree thinking it was a cloud before she has the chance of realising.