I pray the 100 string prayer-beads every morning as I walk from my wife's office to mine, which is roughly 10 minutes. Ten prayers are to Saints (One of whom is St Xenia of St Petersburg
). The point being while I am walking in the street, my lips move slightly, but I am silent.
As John said, the Holy Spirit makes it possible. Before I start praying, I ask the Holy Spirit to present my prayers before the Father as a pleasing fragrance from this unprofitable servant.
I can not say that my prayers are heard by those Saints, but I believe they are. I can not say why, but I believe they do.
Kolya