(Making sentilences) Please correct sentences that are in mistake :)

1. Hit the ground running
- My new chapter has just begun. I hope to hit the ground running soon.
Fixed: My new chapter has just begun. I plan to hit the ground running right away. 

2. Mutually beneficial
- I think we should go for plan B to mutually beneficial for both of us.

Fixed: I think we should go for Plan B because it will be mutually beneficial for both of us.

3. In the black
- I thought it's risky to invest the companies that are not in black. But I realized that some companies are in red due to a lack of financial capacity.

Fixed: I thought it's risky to invest in companies that are not in the black. However, I realized that some companies are in the red due to a lack of initial funding, not poor financial management