I guess "use only twice" means I get to travel through time and then use the second trip to get back to the present if I want to or "retire" in some other time.

No question I would set the time machine back to 1963 and live back then until 1969. I would collect all 97 missing episodes of Doctor Who and whatever other lost media I could get my hands on. After I watch the moon landing live on TV I would return back to the present.

No, I wouldn't try to prevent the Kennedy assassination. The movie Running Against Time has already taught me that's a bad idea.

If "use only twice" means I get two full round trips in a time machine then after going back to the 1960s I would head 22 years into the future to the year 2040 and gather as much information as I can about what will happen in the upcoming two decades and end my journey in 2009 to manipulate bitcoin prices until the present time.

Wait a minute...Is that already happening? Do I get my hands on a time machine someday? Hhhmmm...

Interesting question. Usually, people fantasize about time machines and time travel because of two reasons: 1) because they don't like how their life looks now and are imagining a better alternative through time displacement, or 2) they are immensely curious about time travel.

I happened to fit into both as a kid and have asked myself this question a few times throughout my life.

I have two sets of answers: one from when I was a child and one from when I was a teenager.

As a child, when I entered school age, all I wanted to do was to go back to the time when I didn't need to go to school and watch cartoons all day long. That was wish number one. And then, I wanted to go to a time when I was like my parents - adults who didn't need to go to school but weren't necessarily watching cartoons at home either. That was wish number two.

And then when I grew up and became a teenager, I wanted to experience the carefree nature of a child again. Wish number one. And then, again, I wanted to become an adult and leave start leaving my mark in the world. Wish number two.

These days though, I find myself wishing to go nowhere else but here, enjoying the present, not dreaming about any future or past.

So I guess if I find a time machine, I'll not use it, but pass it to someone else.

Do an infinite loop........like a genie giving you 2 wish, just wish for more wishes.

Do past (like go gack to see the pyramids and hide your finding somewhere you know now one will look for thousands of years).....then come back to just before you left ....and tell yourself what you did and then use the 2 time travel differently.....togo the future, see the wonders, find 10 best things to invest in today, and go back to just before you used the time machine and tell yourself.

Rinse, repeat....LOL. this is time paradox, go figure :P

I would go back in time (1st use) to 2009 and invest all my money into bitcoin. Then return to the present (2nd use) and check my bank account .