Disney World is a lot of walking. A LOT! My daughter is 6 & we end up renting a stroller for her come evening as she is just dragging...& that's with a 6 year old that walks with me at home often!
It's great to have the backup of being able to rent a stroller. Stroller rental costs $15 per day for a single, and $31 to rent a double. If you realize that you will need the stroller for several days, you can rent at the multi day rate of $13 for a single & $27 for a double.
A good thing to know is hold onto your stroller rental receipt! If you "hop" between parks you'll be able to show your receipt at the next park & get a stroller without paying twice. Or, if your stroller gets misplaced or taken by another guest (weird as it is...it can happen, so don't leave your valuables in it!) you can get it replaced by showing that receipt.
My family brings along ribbons & bandanas/scarfs to tie around the stroller handles so that we can find it easily in the sea of strollers parked outside of attractions.
When my kids were 2 and 5 we rented the double strollers and the two of them fit just perfect in there & it was much easier on all of us.
Thanks so much for visiting with us here at Disney World Moms Panel! I hope you have a great time in Disney World!