My husband and I graduated two weeks ago. He wants to do interval training alongside runs and we’ve done two sessions. ( He was a youth rugby coach in younger days). I’m finding it fun but very hard going. I’m worrying that my running will fall behind if I don’t keep it up. We’re doing our first park run on Saturday though. I’m wondering, is there an interval training app like C25k we could use alongside our runs? We did a few laps during our session and I found it so hard- why? Thanks for any advice given.