Tomorrow morning)

Hello everybody!

I'm going to run distance 6.25 miles tomorrow morning.

I'm going to run a distance of 6.25 miles tomorrow morming.

or

I'm going to run for 6.25 miles tomorrow morning.

or

I'm going to take a 6.25-mile run tomorrow morning.

But don't have strength and wish((( Besides I have pain in my left leg.

(I don't understand what you're saying here, so this is a guess)

I don't have as much strength as I'd like, and, besides, I have a pain in my left leg.

I'll hope to be all right.!!

I hope I'll be all right!

(Usage note. In informal notes or texting or forum posting you could have more than one exclamation point, but in careful English you would never use more than one. And you would never combine it with a period).