From a time standpoint I feel relief knowing the importance of intervals because I don't have time to jog long miles everyday, but I do have time to do 2-3 intervals a week with activity in between.
When my boys are in karate 2-3 x/week that's when I've been doing my intervals either on the treadmill or on the spinning bike at the gym. It doesn't take me more than 20 minutes, so now I have time for sit-ups each time and an upper or lower body work out with weights. I've alternated upper or lower body. I have a few dumbbells at home, so with 4 sessions (1 at home), I can do upper twice a week and lower twice a week.
Scott (and sometimes friends) have made it a point to go kayaking once a week. Each trip varies depending on who we are with. This can be my longer more recreational and fun thing to do.
I still like walking, swimming, biking, and yard work (well, I do yard work, don't like it). I fill in the rest of the days with those activities.
I sure do think the intervals have made a difference. I notice in just a month, I am more toned and fitting into clothes better. Since I posted the 167 photo, I am 164. yeah.