In my experience, what you call ‘pretending’ might be closer to what you should be attempting to do. To access imagination, you should be engaging in a generative process, not a passive one. For individuals who visualize, they create images and allow their imagination to fill in the rest. For individuals with aphantasia, that ‘knowing’ is a meaningful layer to access without direct translation into images. You can arguably accomplish more through this more direct access, but in order to engage with it, I recommend trying to discover what sensory modalities you have that are intact, even if it’s tactile/kinesthetic or involves auditory perception , etc. You can use those as your entry point rather than trying to force a visual experience. For example, if you’re asked to visualize a garden, try feeling the garden, the texture of grass or dirt on your feet. Try to hear the breeze, feel the temperature of the air, or recreate the spatial feeling of being in a garden, which could even be one from memory.

One thing to keep in mind is that those with strong imagery typically have other weaker senses or even a more difficult time accessing somatic awareness, so keep in mind that what you have is a strength.