We are joint heirs with Christ, if we suffer with him, so that we may also be glorified with him (Rom 8:17).
The order matters. His sufferings first. His glory after.
The glory outweighs the suffering
Present sufferings are not worth comparing with the glory that will be revealed in us (Rom 8:18).
Paul takes the suffering seriously. He puts far more on the other side of the scale.
Paul says the same in Philippians
Philippians 3:10-14. To know Christ. The power of his resurrection. The fellowship of his sufferings. Being conformed to his death.
In 3:11 Paul writes “if by any means I may attain to the resurrection”. Attain means to arrive at, to come to share in. It describes a destination he is pressing toward. It expresses no doubt.