[bill]

I run up to 30 miles a week, in summer mainly trail. I am male and 72 years old and thank God have no issues with knees, shins or any other body parts. I always want to increase my speed but no fartlek, tempo or whatever is good for me because I have absolutely no concept of pace - I haven't a clue about my speed at any given time. I start off fairly fast and as I tire I slow down, ( I think). I'm quite happy in my running, should I just continue as I am?

 

[Stupid Beard]

If you're happy, what does it matter?

Fartlek is the easiest of the things you list because it is literally just picking up the pace for a random amount of time or distance. You can do that any time; just pick a random tree in the distance and run faster until you reach it. The actual pace doesn't matter, only that there's a difference in pace.

If you have any kind of time goals for races then you might want to try and do speed work. It doesn't take all that long to learn what various efforts feel like. Joining a club will help immensely with that. Most clubs will cater to people of all ages and abilities. It is worthwhile for the social aspect too, even if you don't care how fast you run.