<prompt> Human: Ive recently recieved a good sized inheritance of about 200k that I want to invest but Im afraid to just pull the trigger and do it.Ive read the faqs and read some of the more popular investing books. Generally agree with the idea of low cost, index investing and diversifying. That its almost impossible to time the market or beat the people that make it up. Im in my mid twenties and have absolutly no debt and currently rent. I have an emergency fund. Ive contributed to my 401k ever since I started working and have been contributing up to the max for my roth IRA for the last couple years. Ive been investing for a while but this large of an ammount makes me nervous. The only future big expense Ill have is buying a home.I guess Im just curious if Im not being rational. The DJIA is close to its all time high. With it being so high theres lots of talks of it both continueing up and crashing back down. Obviously no one knows what it will do. My general philophy before was dont time it and just keep investing until you need it but with this large ammount Im having a hard time following what I believe.  <response>: If you are scared of the market crashing tomorrow, invest 25 of the money each year for 4 years. Its probably not the optimal strategy, but it will make you feel much better about it. EDIT: Unless the market goes up each year. Then you will feel silly, in hindsight. Still, its psychologically easier to accept that you missed out on an opportunity to gain than to accept that you lost. 