<prompt> Human: If you look at the SP 500, Dow, Nasdaq, etc. its been on a steep upward trend for the past 5-6 years. If you look historically, this is just about the exact time frame when a recession typically occurs.I have a pretty significant amount of money to invest. Im looking at maxing out IRA and 401k contributions as well as having a decent amount left over to put into whatever other investment vehicle I decide.Im nervous about putting all of this in the market right now because it seems inevitable that in a few years my portfolio will be worth significantly less. But Im obviously nervous about waiting for a recession to try and time the bottom of the market and missing out on 3 or 4 more years of record gains.ThoughtsAdvice? Are my concerns valid? Anyone else experiencing the same anxiety?  <response>: Are my concerns valid?No. The market is usually at an all time high, plus timing the market in a way that maximizes profitability and minimizes loss is impossible to do over long periods of time. Time in the market, on the other hand, does exactly that. 