To prevent boredom, I like to switch up my workouts. I don't need a personal trainer. I have a few training videos and I subscribe to a few fitness magazines, and I get all my ideas from them. I have a workout binder, and I keep all my personalized workouts in there. I cut out the exercises I like from magazines and paste them into a scrapbook under "arms," "back," "abs," "legs," etc. I then keep a master library of each exercise in the front.
On my slow days, I do a workout for a timed amount of time (an hour), and circuit train, picking one exercise for each body part and rotating around. For example, I'll do 30 crunches on the ball, then 10 one-legged squats, 10 triceps kick-backs, and 10 biceps curls. It allows me to experiment with different exercises, keep my mind interested, and challenge my body. I'm always sore the next day.
You can do the same with running, biking, and swimming. This is handy especially for the trainer or treadmill. I was getting sick of my workout videos but wasn't motivated enough to cycle hard on the trainer on my own.
Last night, I really wanted to watch "30 Days," so I got on the trainer and started a timer. I warmed up for 5 minutes by pedaling quickly on a low gear. Then I did 3x1 min sprints on a low (but slightly higher than warm-up) gear with 30 second rests (rests were same intensity as warm-up). After 1 min. rest, I did 3x5 minute 90 rpm sets at a gear high enough to keep my heart rate about 140 bpm. I allowed myself 1 minute active (warm-up inten sity) rest between each set (allowing my heart rate to fall no lower than 120). Following this, I did 3x4 minute sets at 100 rpm (slightly lower gear), again using my heart rate as a gauge to set the gear with 45 seconds active rest between each set. Then, I did 3x3 minute sets at 110 rpm, slightly lower gear with 30 second rest between each set. I finished with a 5 minute cool-down. Don't forget to drink a lot during the rests and stretch afterwards!
This is my "base-building" workout that I adopted from Spinervals. I like it b/c it's simple and you can watch t.v. while doing it or listen to music. You don't have to think too hard. Plus, you can always add or subtract sets as needed.