I mean to do it regularly. Ideally, every day, even if just for 5 minutes.

Personally, I sit in a dark room, on a one-person couch with no armrests, so I can bend my knees and open my legs butterfly-style with the soles of the feet touching. I put a firm cushion on my back to keep it straight, keep myself at a 90° angle.

Always paying attention to my breath, releasing whatever is on my mind at the moment of exhaling, while trying to not do anything (now there’s a paradox), to let go and just observe, returning to the breath, returning to the breath, returning to the breath.

I started doing this for 10-15 minute sessions, worked up to 25 minutes, jumped to around a full hour, and have settled on around 45 minutes.

Sometimes, I’ll do this in the backyard. There’s loud traffic nearby, including trailer trucks, but there’s also some beautiful birdsongs coming from the trees.
And in theory, one is supposed to be able to meditate perfectly fine even if there’s a jackhammer operating by your side.

You could also focus on the breath while thinking something along the lines of:
“I am calm…” while inhaling, then “…and I smile” while exhaling.
You could do this at the start, at the end, at the middle, during the whole session, not at all… there are no fixed rules, do what the moment calls for, go with the flow. Do it until you… stop. By that token, also don’t do it until you start.