The one decision that will affect EVERY area of your life meaningfully is picking the right partner. 

This is because, your partner affects: 

– Your financial life:
To have the same financial goals and use money in similar ways makes life less about convincing and figuring out, and more about living it together.

– Your physical life:
Your workout habits, your eating habits, your binge-eating habits, your sleeping habits – all have a direct impact on how you live your life.

– Your emotional life:
Stability in your relationship with your partner will eventually determine how emotionally stable you are in every other relationship you have.

Making this one decision wisely will determine almost everything in your life, meaningfully.
Not to be made in haste :)