I was nearly 17stone when I started running. I would only run after dark because I was too embarrassed to let people see me. C25K came first, and once I did that I did some parkruns but I was still really really slow. 43min time.
Then a friend of mine came out with me a few times during the day, and I gradually started to relax about my size, I'd actually lost half a stone by this point and I started to up the distance slowly. I then entered a 10k race to give me a bit of ooompf and motivation. I was 16st7 when I ran that 10k, it was hilly as fuck and 30deg. My friend (who is a 52min 10k woman) stayed with me every step of the way and I finished in 1h21, with only about 100m of walking.
I then started to take my diet a bit more seriously, this was now August 2017. I did a couple more 10k's over the autumn and eating mindfully and I started to lose more weight, by Christmas 2017 I was just over 15st.
January 2018 I did RED January and it was probably one of the hardest things I've done, but I lost another stone that month.
First half marathon was May 2018 - 2h11 which I was amazed with! Again a really hot day, but flat this time.
I then lost focus over the summer and put a bit of weight on, so I entered another half marathon for the October with the aim of going under 2 hours. I was down to about 13st7 by this point. I did that half in 1h59:10, squeaking in by the skin of my skinny teeth, and just tipped into the 12st bracket.
Over November/December it all went a bit Pete Tong, and I put half a stone back on. So obvs the thing to do was to enter a marathon for April 2019 (14th, 13 weeks to go NOT THAT IM COUNTING). I'm now just over 13st, I really need to be about 11st7 to be a healthy weight so it's ON.
My lovely friend is with me every step, and I've managed to get another friend running as well and we regularly do 10k together.
It's been a slow slow journey, but I'm mentally and physically so much happier.
The first run starts with a single step, and C25K is somewhat akin to witchcraft in my opinion.
Currently my PB's are 5k 24:58, 10k 54:50 and half 1:59:10 but it's taken me 2 years and some serious sweat (and some excellent boob support!) to get here. Just do one run. And then the next one. And then another one.
Sorry for the essay. MFP has been vital as well, I eat all my exercise calories, try for 12-1400 net calories per day and the weight loss has been slow but obvious.