When I started C25K in November my progress was quite linear. I was lucky enough to be able to accomplish my runs each week without having to repeat any and planned to consolidate for a bit before starting my progression on to 10k which I believed would also be just as linear.
Boy was I wrong two different issues with thyroid medication being off has meant that run frequency went down as well as distance/speed. This was really frustrating even after dosage was changed as it takes time to kick in. Saying that my running was what convinced me both times to approach my GP for bloodworks and I would have held off much longer if I did not see such a decline in my ability to run distances that just a week or two before had been easy so it helped to resolve the issue much quicker.
I am not going to lie the last 10 or so weeks have been frustrating as my thyroxine was adjusted twice and there have been many times when I was so tired I could only get two runs in or would be angry that I had to quit after 20 mins even at a slow pace. There were times that I wanted to really give up and come back to it later (or probably not at all as once you stop it is hard to get back into it).
I am so grateful I pushed on and did what I could when I could. Going on three weeks since my latest thyroxine dose was upped and I had the courage to go back to a running group I had tried just after Christmas and together with a good running buddie we ran my longest distance to date (6.5K) with that running group. I also took two and a half mins off my Parkrun PB yesterday and ran at pace that even before the thyroid issue I thought would take me until mid to late summer to get to. So all those runs when I was so slow or had to run less per week were worth it even if they didn't feel like it at the time.
I could complain that by now even with a 4-6 weeks of consolidation after my C5K I should have been done with a B210k program but life doesn't work like that and I managed to keep going through the hard times instead of giving up. Running has taught me so much about perseverance, listening to my body, knowing when I was unwell and to seek medical attention sooner and trust myself. I have made a great friendship and running partner with a casual acquaintance who also happened to be doing C25k and then B210k. HealthUnlocked has been such a supportive community as well.
I guess all this rambling is to say don't give up even when it seems like the effort isn't worth it. Don't give up when you can only get one or two runs in instead of three. Don't give up when you have to stop after twenty minutes. Even the day you feel like you are failing are pushing you to something better in the long run. Sometimes the lessons you are learning are not how to up your pace or distance but are about life.