Don’t depend on willpower. Lower (or increase) friction. If you have trouble with not eating cookies, increase friction by keeping them out of sight, or just don’t keep them in the house. If you have trouble getting to the gym, reduce friction by getting everything ready the night before - put coffee or your workout drink in an insulated flask, have your gym clothes out (or sleep in them), etc. If you have trouble waking up in the morning, increase friction (for staying in bed) by moving your alarm clock to the other side of the room.

What are some of your top “life hacks” to “speedrun” through certain things in life?

Be born to a rich and well connected family.

and where shouldn’t it be applied?

You shouldn’t try to speed through life. The journey is the destination. We all know how life ends and it’s not really that great, so no point in rushing it.

The funny thing about life is that it takes a long time to build something or get it done, but the only things you can accomplish with a speedrun is to burn it all down.

Invest in index funds ASAP. Money put into a diversified portfolio doubles roughly every 10 years. Meaning for every 10 years you wait, you need to put twice as much money in than you otherwise would have. This is massively helpful when you need a down payment for a car/house and eventually for retirement. DO NOT UNDER ANY CIRCUMSTANCES look at the money in the account often, this is a long-term investment, not something you stress about every day because it happened to decrease 0.5%. This is money to be left in the account for a decade or more.

Specific suggestion: Put 10% of every paycheck into an index stock like such as VTI, which is a total stock market index fund.