This is my interpretation of the song, in a key in which the song was commonly sung. 

I Just Can't Help Believin'
Sung by B.J. Thomas (and others)

Capo 3

Intro:    D  Dsus4  D  Dsus4

            D                                  Dmaj7
Verse 1:  I just can't help believin' when she smiles up soft and gentle,
                 Em                           A7                         D  Dsus4  D  Dsus4
          With a trace of misty morning and a promise of tomorrow in her eyes.
                D                                    Dmaj7
          And I just can't help believin' when she's lyin' close beside me,
                 D7                                 G     Gm
          And my heart beats with the rhythm of her sighs.


          D             G             D   G
Chorus:   This time the girl is gonna stay,
          Dmaj7         G6            A   Asus2  A
          This time the girl is gonna stay
                               D  Dsus4  D  Dsus4
          For more than just a day.


            D                                  Dmaj7
Verse 2:  I just can't help believin' when she slips her hand in my hand,
                 Em                                  A7                            D  Dsus4  D  Dsus4
          And it feels so small and helpless that my fingers fold around it like a glove.
                D                                    Dmaj7
          And I just can't help believin' when she's whisperin' her magic,
                  D7                                 G     Gm
          And her tears are shinin' honey sweet with love.


          D             G             D   G
Chorus:   This time the girl is gonna stay,
          Dmaj7         G6            A   Asus2  A
          This time the girl is gonna stay
                               D  Dsus4  D  Dsus4  D
          For more than just a day.