to participate in an enjoyable activity
an einer unterhaltsamen Aktivität teilnehmen (an einer unterhaltsamen Aktivität teilnehmen)
"Even the shy guests joined in the fun after a while."
"Selbst die schüchternen Gäste machten nach einer Weile mit." (Selbst die schüchternen Gäste **machten nach einer Weile mit**.)
to reflect on your own emotions and motivations
to detect or receive a wireless signal
to go beyond what is normally possible or expected
to organize efforts with people in different countries
to start something without using anything that already exist...
to verify or ensure that something is being done correctly