I have a smoothie three mornings a week and I have found it an easy habit to maintain.

Psyllium powder swells up dramatically into a gluggy lump which would be impossible to swallow without causing harm. I was in a hurry one day and decided to try mixing psyllium powder in about half a cup of water (which is approximately 125 ml of water) and I had to keep adding more water, more water and it took a good few minutes to finally finish the dose. It was unpleasant as well as annoying to have to deal with the residue in the cup. Never again.

I use at least 400 ml of liquid plus the fruit I add to blend into a smoothie.

If it is not possible to make a blended smoothie, it would probably work to put at least a cup and a half of liquid in a shaker to mix it all together. If it was me I'd use milk and probably add some chocolate powder or another healthy flavouring (I'd choose low or no sugar) to make it interesting in place of blending the fruit.

To repeat one of my previous posts, I use a heaped teaspoon of psyllium powder i.e. about 5g and no more. (I just looked it up and capsules have about a tenth of that amount, so very expensive.) Too much is not pleasant - either the process of taking it or the resulting too-efficient effect. A healthy balance is good, more than a heaped teaspoon is definitely not better in my experience.