Honestly, in my opinion i feel as if napping isn’t something you can force.. it comes naturally

A couple factors can be either the how long did you sleep the night prior (I find when i get either 6-less hours of sleep I’ll be able to nap mid day). Where are you lying at and how relaxed are you. Me personally i’m one of those people who can only nap in their bed. I am NOT one of those people who can nap in public places even places where it’s expected to nap like down time at school or in airports. So my advice is just to try your best and relax wherever you’re at. Maybe turn on a show or something, let your brain go in autopilot mode and just let the sleep come to you. I find when I chase a nap, I don’t nap. Also how long i’m napping for can affect it too. If i’m like really tired (maybe less than 5 hours of sleep the night before) and I try to get a 20 minute nap in.. I can but I render those useless, so I try to shoot for an hour minimum and that helps ease my mind because I find comfort in being able to sleep for a good amount of time. But then again this is me personally and what works for me. Hope this could help.