Text: thank you for visiting.

Correct capitalization: Thank you for visiting.

Text: it is important to have a well-functioning digestion.

Correct capitalization: It is important to have a well-functioning digestion.

Text: joule, electronvolt, calorie, british thermal unit, kilowatt-hour, ...

Correct capitalization: Joule, Electronvolt, Calorie, British thermal unit, Kilowatt-hour, ...

Text: it would be nice to not have cold feet after walking around in my home.

Correct capitalization:
It would be nice to not have cold feet after walking around in my home.