What word describes the ability or capacity of oneself on a given day

Solution 1:

According to Google translate, the Swedish word dagsform loosely translate to the compound word "daily form".

A single word for daily form would be just "form", which in sports means a physical state or condition or mood of a player on a given day or in particular time frame or state starting from certain time.

Usage: If you want to use this word for a particular day or certain time frame, then you have to indicate explicitly "today" or "particular time-frame" or "start time" in the given sentence. Check Oxford examples below.

Please check Oxford dictionary entry 8.2 for the word form.

A person's mood and state of health.

"That morning Christine had been on great form but at 8pm her mood changed dramatically."

"And then yesterday I retired to my sickbed, feeling decidedly under the weather, and am still not on top form today."

Synonyms: state of health, physical state, condition, constitution.