Over effort, over focus

Sometimes we try too hard and obscure the thing we want to achieve, especially when it comes to relaxation. There is a maxim in Qigong which says, "energy flows where attention goes". So you can direct your mind to any part of your body and you can feel more aliveness there if you focus properly.
You want to learn a "relaxed focus" not a "tense focus". We tend to associate concentration with tension but one of the biggest keys in Qigong, Taijiquan,
Internal Martial arts and meditation is to learn this tuning of your instrument, "not too tight, not too loose".
Another useful tool is to focus on something else and allow relaxation to be the by-product. For example, if you try to relax, you may mentally tense more by being too vigilant with your level of tension but if you watch the rising and falling of your belly or your breath or your thoughts, you may notice more relaxation at the end of your session.