Mount Coolum hike is a popular walk that can be enjoyed by many. The view at the top is amazing, so definitely spend a while up there memorising the view.
The walk takes approx 1hr up to the top and 1hr down (going down can be faster though). I would recommend taking out 2.5hrs for the whole walk, or longer if your fitness levels aren't too well. The walk includes hundreds of steep stairs, which keeps your heart rate up so definitely be prepared - bring a bottle of water and your running shoes. Once you are at the top you can see the view of mountains and the beach, which is beautiful at anytime of the day, but seeing it at sunrise/sunset would be amazing.
Once you have finished the hike, I recommend heading down to a local beach at Coolum to go for a swim and relax - you deserve it after 2hr+ of exercise!