Psalms 51:10 - Create in me a clean heart, O God; and renew a right spirit within me.
Isaiah 53:5 - But he [was] wounded for our transgressions, [he was] bruised for our iniquities: the chastisement of our peace [was] upon him; and with his stripes we are healed.
2 Peter 3:9 - The Lord is not slack concerning his promise, as some men count slackness; but is longsuffering to us-ward, not willing that any should perish, but that all should come to repentance.
Romans 8:28 - And we know that all things work together for good to them that love God, to them who are the called according to [his] purpose.
John 3:16 - For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.
Hebrews 4:12 - For the word of God [is] quick, and powerful, and sharper than any twoedged sword, piercing even to the dividing asunder of soul and spirit, and of the joints and marrow, and [is] a discerner of the thoughts and intents of the heart.
So ask God to forgive your sins, repent, and let your guilt go. I'm willing to bet your low isn't all that bad, so calm yourself and focus on the race.
And apply and reflect on God's word in all areas of your life.