In 1838 he united with the Methodist church, and it was during the time he was studying law that he felt a call to the ministry.  He immediately turned his energies in that direction and in 1843 was licensed to preach when he was still a minor.  In 1845 he opened a select school in Vincennes, Ind., and in September of the same year was placed in charge of the preparatory department of Asbury University, which position he held until 1849.  During this time he continued his studies, and received the degree of A.M. from Asbury in 1848.

After leaving the university he opened the Scribner high school at New Albany and labored there two years, when, health failing, he took the editorship of the "Oddfellow's Magazine" for a period of five years.  In 1853 he was elected professor of mathematics and natural sciences at Whitewater College, Centerville, Ind., and two years later was chosen president of the institution [sic]  In 1856, finding that his health required active outdoor life, he resigned his position and became financial agent for a prominent Indiana railroad.  He served the road faithfully, was agent for the Northwestern University for a short time, then accepted a pastorate of a Des Moines, Ia., church, and was admitted to the Iowa conference.  In 1861 he was elected president of the Iowa Wesleyan University and pastor of the university chapel.  Later he was pastor of Asbury chapel at Mount Pleasant, Iowa, whence he was called in 1864 to the presidency of Albion College.

Dr. Jocelyn brought to Albion College the rigid training and deep culture of half a life time.  He abolished the scholarship system and put the endowment plan on a firm basis.  For five years he worked with heart and soul in the interest of the institution until he had exhausted his physical powers and resigned to accept an appointment by the conference to Division Street M.E. church in Grand Rapids.  His masterful executive ability was greatly missed by the board of trustees however, and he was pressed to return after a year's experience with William Beinhauer Silber and J.L.G. McKeown, two men who were secured from other conferences to head the institution and whose administrations are recorded as extremely short-lived and unsuccessful.

In 1871 President Jocelyn returned to assume his duties in charge of the institution.  This time he was to devote his life to the work of of [sic] his choice, for six years later, on January 22, 1877 he passed away after a sudden attack of sickness which seized him while in the lecture room at class one winter morning.

As a man Dr. Jocelyn was frank, earnest and persevering.  When he had once decided upon a course of action, he never faltered, however great the difficulties to be surmounted.  His name and repute will long live in connection with Albion College and Michigan Methodism, as his integrity placed him in the very first rank of eminence and usefulness in both.  He gained a strong hold upon the affections of the students; his great goodness, warmth, pleasantness, and sociability, winning for him hosts of admirers.  His executive policy was liberal and yet with no laxity; he was ever firm in the right but not tyrranical [sic].

Dr. Jocelyn was married in 1845 to Miss C.M. Lyons at New Albany, Indiana.  He was a prominent member of numerous fraternal organizations and for one - The Temple of Honor - he wrote the society ritual.  Politically he was a republican but in the later years of his life became a strong prohibitionist.  Both Kentucky and Asbury universities conferred the doctors degree upon him.