A walk around the lake can be a nice evening stroll after dinner or a quick hike round for some serious exercise. I found it seemed less strenuous if walking clockwise, however that might just have been the beer!
Starting at the Hotel Toplice and going clockwise, you pass through the hamlet of Mlino with its bars and cafes. Then the path leaves the road to continue closer to the shoreline. At the far end of the lake is Bled campsite, and this end tends to be noisy and crowded on warm days as they all rush to swim in the lake. Just past the campsite are the stands for the boat racing and you will often see them practising on the lake for the regatta in June. Further round you will see the Castle Baths--small pools and a roped off area of lake. Then you pass the path to the castle and also the parish Church of St. Martin before strolling through the park and back arouond to where you started.
It's pretty much flat all the way round and for the fitter you can walk it in an hour the less fit might need one and a half hours. It's pretty and there are lots of trees, ducks, lillies, swans, and fish to see on the way.