From the locality of San Giorgio all'isola, along the lake of Gerosa, take a cartroad and then the white road that leads to the hamlet of Altino di Montemonaco. 
From here you take the path in a westerly direction along a stretch of the Grande Anello dei Sibillini, known as the "path of the reapers"; from Monte Oialona you go down again to the lake along single track through luxuriant beech woods. 
Alternatively, you can reach Balzo di Montegallo and the small villages of Propezzano and Polverina, thus avoiding the single track