<prompt> Human: I know this is basically market timing, which is a bad bad thing, but... It doesnt seem unreasonable to expect relatively low returns for the next decade based on historic market highs and Im not alone in this, the CEO of much beloved Vanguard said recently it would be reasonable to expect 3 returns or so for a while. Given that, and returns on a mortgage of about 3 does it make some sense to put some investing money towards mortgage principal instead for a while. Maybe Im fishing a bit for some rationale behind paying off the mortgage a bit due to the psychological benefits of paying down debt. Any thoughts? Dont time the market...? Bank on more historic return like 7...?  <response>: It doesnt seem unreasonable to expect relatively low returns for the next decade based on historic market highsSure it does. Its basing future performance on past performance, which is irrational and doesnt work and is market timing, which also doesnt work.Vanguard said recently it would be reasonable to expect 3 returns or so for a whileUmmm...no Markets generally return about 7 - 8 per year. A bit below isnt 50 off average returns for a decade. Thats a total collapse.oes it make some sense to put some investing money towards mortgage principal instead for a while.Youd make more investing in stable index funds that focus on dividend paying stocks or preferred stock. If you feel better by doing it, go for it, but dont pretend it makes sense because youre artificially chopping expected market performance. 