How do you actually manage separable verbs when speaking quickly?

I'm a busy professional with maybe 20 minutes a day to study. I feel like I've got a decent vocabulary, but as soon as I try to use a separable verb like 'opbellen' in a sentence, I freeze trying to remember where the 'op' goes—especially if the sentence gets longer. It feels like I'm doing mental gymnastics while trying to talk. Is there an effective way to drill these, or does this just eventually become muscle memory? I am asking specifically about learning Dutch, not a generic study routine.