We are not called to rejoice at suffering in and of itself. Suffering is bad, suffering is hard, and suffering often comes at the hands of wicked people. Therefore, we do not rejoice in suffering because we love the suffering in and of itself. We rejoice in suffering because we look forward to what God is able to do through our suffering. Paul [in Romans 5:1-5] celebrated the fact that through our sufferings and afflictions God is bringing about endurance, proven character, and hope.
Heath Lambert