By (δια). The intermediate agents of the exhortation (the Lord Jesus and the love of the Spirit) as δια is used after παρακαλω in Romans 12:1.

That ye strive together with me (συναγωνισασθα μο). First aorist middle infinitive of συναγων ζομα, old compound verb, only here in N.T., direct object of παρακαλω, and with associative instrumental case μο, the simplex αγωνιζομενος, occurring in Colossians 4:12 of the prayers of Epaphras. For Christ's agony in prayer see Matthew 26:42; Luke 22:44.