This sonnet, written by John Donne, is penned in iambic pentameter. This means that each line contains ten syllables each, grouped into five (hence, the prefix "penta-") "feet" or two-syllable pairs. The particular type of "foot" used in this style is known as an "iamb," which is an unstressed syllable followed by a stressed syllable. Thus, we can conclude that the ten syllables in each line will follow a pattern of unstressed syllable, then stressed syllable, unstressed syllable, then stressed syllable, and so on and so forth.

With that in mind, let us do a traditional "scan" of the poem so that you can see this visually. I will put the stressed syllables in a bold font and let the unstressed syllables be italicized. I will also separate out each iamb with a single vertical line ( | ), so you can see how there are five iambs in each line. You will naturally notice that some polysyllabic words will contain both an unstressed and stressed syllable. You will also see me split words when they are divided across feet "breaks;" I will indicate this with hyphens (-). This may sound complicated now, but I assure you that it is much easier to understand when seen! Let us take a look: 

Thou hast | made me, | and shall | Thy work | decay ?
Repair | me now, | for now | mine end | doth haste;
I run | to death, | and Death | meets me | as fast,
And all | my plea- |sures are | like yes- | terday.
I dare | not move | my dim | eyes an- | y way;
Despair | behind, | and Death | before | doth cast
Such ter- | ror, and | my fee- | ble flesh | doth waste
By sin | in it, | which it | towards hell | doth weigh.
Only | Thou art | above, | and when | towards Thee
By Thy | leave I | can look, | I rise | again ;
But our | old sub- | tle foe | so temp- | teth me,
That not | one hour | myself | I can | sustain.
Thy grace | may wing | me to | prevent | his art
And thou | like ad- | amant | draw mine | iron heart.