Love? The best in my opinion and the most universal symbol for love (also in Poland) is a red heart. The second place I would give for red rose.
Strength. In Polish culture 'dąb' (oak tree) is associated with strength. There's even a saying in Polish: "Silny jak dąb" (Strong as an oak). Another Polish strength symbol is Mariusz "Pudzian" Pudzianowski - known ex. strongman ;)