If you earned at least $400 in self employment income which the income from Lyft is, you have to report it on Sch C and pay self employment tax.
You have to enter self-employment income if you made even $400.
https://ttlc.intuit.com/questions/2903027-how-do-i-report-income-from-self-employment
https://ttlc.intuit.com/community/self-employed/help/what-is-the-self-employment-tax/00/25922
https://ttlc.intuit.com/questions/2902389-why-am-i-paying-self-employment-tax
https://ttlc.intuit.com/questions/1901340-where-do-i-enter-schedule-c
Tax Tips for Uber, Lyft, Sidecar and other Car Sharing Drivers FAQ
https://turbotax.intuit.com/tax-tools/tax-tips/Self-Employment-Taxes/Tax-Tips-for-Uber--Lyft--Sideca...
https://ttlc.intuit.com/questions/3398950-what-self-employed-expenses-can-i-deduct
