I've been a writer for a while and here is my advice:
To keep reader's interested, add details but make them relevant and tie them into the plot. As in, add details but make it so that the extra details serve a purpose of helping the reader's form a mental picture.
Example:
"Applejack pulled out an apple and ate it"
Bad detail expansion
"The happy Applejack pulled out an apple and ate it on a Saturday afternoon at 9:00 AM"
Good detail expansion
"Applejack smiled, and pulled out a red apple, then hastily ate it, much to her satisfaction."