I'm in my late 40s, thinking about getting back in some semblance of race shape this coming spring but have just been doing casual miles for the last 10ish years. I typically do 30ish mpw at 7-8 min pace. When I have time off I do more - dropped a 60 mile week over labor day for example, will probably do the same over Christmas. But haven't done any speed, threshold, etc. in a long time and my lungs just aren't there any more at faster paces. My sense is to keep it simple, start with a 30ish minute tempo and a longer run built into my week and see where it goes. Curious if any masters runners have advice for switching back out of casual mode.