With lots of tiny parts moving at high rates of speed you want it to last a long time. Breaking in an engine helps seal the pistons rings into the cylinder surface. Without a proper seal you end up with engine issues, sometimes sooner rather than later, but almost always inevitably later.
The old school way of thinking is heat cycles. The "three heat cycle" seems to be most popular. Turn the engine on, let it idle for 10 minutes, give it a couple of revs, then shut it down. Cool off completely. Repeat. Repeat again.
All the new parts in the engine are mating together and the aluminum parts need a chance to expand, from the heat, fully. Riding before the engine is warm (and this reflects both the heat cycle routine and the controversial ride it hard off the floor) can cause the pistons and rings to sit prematurely causing wear and potential damage.
Make sure your oil level is middle of the stick (not screwed in) Let the bike warm up normally, then ride the bike for around 10-15 minutes at a decent pace but without over-revving the engine. Then let the bike cool down for around 20-30 minutes. Then repeat this 3 or 4 times. On the 3rd and 4th time I usually ride a bit longer, 15-20 minutes.
Oil is 10w30 or 40 absolutely no more than 700cc from complete drain. Change after break in completed.
Fuel premium or no ethanol recreational fuel 92 octane