Mix 'n Match Hymns
Nearly every hymnbook will show, usually at the top of the page, an abbreviation of the metre of the hymn, e.g., CM, LM, SM, LMD, etc. (which stand for, respectively, common metre, long metre, short metre, long metre doubled). These are standard arrangements with a certain number of lines and a certain number of syllables per line. So if you get tired of singing The Church's One Foundation to the usual tune, known as Aurelia, you look for another tune with the same metre and it will probably fit. Many hymnals have an index with all the tunes sorted by metre to make it easier to find an alternate tune. There are, of course, some hymns which have been sung to different tunes for eons, so there may be two or more versions in a hymnbook. For instance, Jesus Lover of My Soul, a Victorian favorite, is sung to 3 different tunes.