It is natural to face this type of "limits".
The energy you invite when meditating is transformative.
This means that it changes mind sets and patterns in you.
When this happens, there is a conflict between two streams of energy.
The first one is the energy you invoke trying to break through and free you.
The second one is the existing one. It represents the patterns which are already established in you.
If you jump in cold water, it gives a shock to your system, right?
This shock is the result of a "clash" between two temperatures: your body temperature and the water temperature.
Same happens with a meditation technique.
The moment you invoke a fresh energy, it finds its way into your mind until it meets a resistance zone.
These resistances are simply your existing mind patterns.
Some of these mind patterns are old and no longer needed.
For instance if you have an old negative memory about a past event, it is a mind set which is no longer needed.
Now, part of you naturally holds to it.
It is not a conscious decision: memories are naturally sustained in your mind by what you can call preserving forces.
When a fresh energy comes in and naturally targets this old pattern (it happens naturally, organically. It is not a conscious decision on your side), a natural clash of energy happens.
It is a clash between an old mind set and a new source of energy.
Imagine: it is like lava under a volcano trying to break through.
This lava faces rock resistance and opens new channels of energy within the volcano.
The conflict between the lava and the existing rock formation is exactly what you experience on a mind level.
When this happens, you don't have to repress your anger or frustration.
Stand up and do some martial art techniques like punches or kicks with "Kiais!".
You have an excess of fire and you can use this fire to help the new energy break through.
You can for instance do some light jogging, go in nature and get rid of the excess of energy.
You can as well use it to do some power training or even join a kick boxing class.
What matters is that this anger or frustration is actually a good sign.
It is the result of a fresh energy breaking free in your system.
Your emotional reaction is the expression of fresh energies breaking through.
In the same type of situation, some people will actually feel laughter coming in rather than anger.
You can give it a try: next time you feel angry or frustrated, try transmuting this emotion into laughter.
The effect is the same: breakthrough of energy.
If you don't resist this emotion, you will notice that it naturally finds its way out.
If this happens again to the point where you are truly boiling internally, shift activity, stand up and practice some of theses martial art techniques.
Use this excess of energy to break open new doors in your system.