
Your question makes it seem that meditation is something similar to mountain climbing. But instead please look at meditation as a pause during or after the mountain climbing, when you simply do nothing but completely rest. Mental non-doing being, complete cessation of mental activity is what will get you to the energy vibration frequency of theta. All the doings that you are talking about will only keep you firmly rooted in Beta frequency.
Deep breathing is not meditation. It is a physical exercise. It is not even yoga or pranayama. Pranayama itself is a gentle practice (like Anulom Vilom) that can become intensive sometimes (like kapalabhati) but these are not meditation, these can be used as a stepping stone to prime the mind for the meditation practice. Or you could first shift your mind into a meditative state (alpha frequency) and then do pranayama while continuing to remain in the alpha frequency. That could make the activity of pranayama into a practice of meditation. You could do the same with walking or dish washing or any activity. Chanting a mantra is also similarly an activity. You can do mantra chanting as a primer for the mind before the meditation practice or you can sit with the mantra practice after the mind shifts into the quiet aware mode and you are able to be a witness to the mantra chanting happening in your body in sync with your breath automatically without any mental effort. This is used for practicing sitting with meditation for long durations, but it is recommended usually to drop the mantra and simply sit with awareness once the mind goes very still and quiet and these tools are no longer needed. Beware of the tendency to force your mind to be free of thoughts, you may be able to sit without any thought but still it would not be meditation unless it happens naturally after releasing all the restless energies into the earth. Read the second link pasted below to understand this more clearly if required.
All the techniques and tools are needed only to settle the restless state of our minds which is habituated to keep doing and never stop doing.Once we regain our connection with earth energies we experience a mental shift into a vibrational frequency that corresponds with Alpha.The alpha state itself is a deeply healing and rejuvenating practice and it is enough to be here to heal and transform your life. When you continue to use tools such as mantras or focus on breath or tapping or any physical doing to help keep your mind quiet, you will be able to stay in alpha state and deeply heal.
But if your goal is to go deeper into theta state, it is simply a question of sitting in non-doing being. All the concepts and techniques that apply in the normal world doesn’t apply here. Repeatedly choosing not to engage with arising phenomena and simply coming back and being an aware non-doing witness to all the arising phenomena helps with moving from alpha to theta. Remember that it is a slower vibrational frequency. You are moving towards zero here and any effort or wanting, to reach the destination, only tends to increase the vibrational frequency not decrease. “Raising higher to theta frequency” or “sinking deeper into theta frequency” are all words used as a figure of speech. You are not going anywhere literally. The source of the universe is not up there somewhere. The centre of cosmos is not out there in deep space. It is right within you. It is everywhere and nowhere. It is a different dimension than the dimension of space-time. Thinking, understanding, striving, etc do not work here.
Please read the following articles to understand the difference between doing a mantra chanting and being with the mantra chanting.

Selvan Srinivasan · 2y
How do you chant “Om” internally?
Chanting OM internally is the same as Awareness of Breath meditation. Once your mind shifts into a quiet mode, simply sit in awareness and be aware of the movements of air in to your nostrils and out of your nostrils. With your intuitive mind you will hear the sound of Oo as the breath flows in and the sound of Mm as the breath flows out. You are not doing anything. Breath is happening by itself and it gives rise to these sounds by itself. You are not even focusing or concentrating on the breath or the sound. You are simply sitting in awareness and the arising phenomena of the breath is happening in the awareness. In addition to the breath, everything else arising or happening in each moment is also perceived by the awareness but you simply choose to sit as a witness and not get engaged with any specific phenomena. A state of grounded presence is essential before you can allow this to happen. For shifting into the quiet mind space Of grounded presence, you may use any effective practices. You can use chanting OM aloud in the beginning, or practice bhramari pranayama for a few minutes, and then soundlessly chant OM by doing the breathing and imagining the sound before the mental shift happens and then you will be able to sit quietly in a state of non-doing being, simply witnessing Om arising and flowing with each breath. You may use the guided meditation audio linked below to practice chanting OM internally. You may read the linked article below to learn other effective tools to quieten your mind to be able to practice this with ease. Selvans Guided Meditation – Awareness of Presence and Arising Breath

Selvan Srinivasan · 1y
How long does it take to get into a meditative state when you start practicing meditation?
You could be sitting for several minutes or even hours but never get into a meditative state even though you have managed to force your mind to have no thoughts by concentrating or focusing all you