How Create Garmin .FIT interval workouts
 

How can I create my traing interveal workouts into a .FIT Garmin file format.
The problem is that I am not a owner of a any Garmin device.
Is there any way?
Regards
Here an example:
10 minutes warmup
10 series of 2 minutes of HIIT and 2 minutes of rest
10 minutes cooldown

I create my workouts in TrainingPeaks. Click a button in the workout and it will download a FIT, ZWO, ERG, or MRC file for it.

It's free to create a Garmin Connect account whether you own one of their devices or not. They have a workout creater tool.

I use trainerday and convert it to fit from mrc using whatsonzwift. (My FTP is still fluctuating so no erg.) The free version of trainerday allows for storage and catalog of my workouts. Training Peaks and Garmin Connect both have free editors. TP (free account) limits the number of workouts you can store and I don't care for the GC's interface.