15 years of solid savings at age 35. Congrats. That is an awesome start to your RE plan.
There is a wealth of info here on the RE withdrawal topic as well as other popular blogs. Check out RootOfGood, GoCurryCracker, MillionaireEducator as just a few of my favorites that focus on building FI and converting to RE.
Popular RE withdrawal/income methods include:
Roth IRA conversion - RootOfGood has a fantastic article on this
http://rootofgood.com/roth-ira-conversion-ladder-early-retirement/457 Plan - IF you have access to one, MillionaireEducator discusses these in a few articles
Taxable Accounts - drive your savings rate high enough and you will eventually build up a nice balance here
72t IRA Withdrawals - rigid plan but one of the above bloggers uses it
Real Estate - rental property income
Sell Primary Residence - significantly downsize and rent, covert equity from the sale to taxable investment account
Inheritance - tough to plan around but some people can so it is worth a mention