The invitation to follow Jesus is an invitation given to the crowd and the disciples (Mark 8:34). Jesus calls everyone who has ears to hear to listen to what he has to say and to follow him (see also Mark 4:9).
Having explained who he is (Mark 8:29) and what he came to do (Mark 8:31), Jesus now calls people to follow him. In Mark 8:34–38 Jesus explains what it means to be his follower. Jesus himself is telling us what true faith looks like. What the response is that he wants from us, now that we know the truth about who he is and what he came to do.
31 And he began to teach them that the Son of Man must suffer many things and be rejected by the elders and the chief priests and the scribes and be killed, and after three days rise again.