Citta vipassana (mindfulness of mind) is difficult if your sati and smathi are not well trained to be quick and strong to detect the change of mind. Kaya vipassana (mindfulness of body) will help. You need to increase your sati and smathi by walking and bodily-movement meditations. You should practice all four foundations of mindfulness including mindfulness of body, feeling, mind, and mental phenomena, not only citta vipassana