Running and strength training are not rivals; they just compete for the same recovery. Decide which one matters most for the next few months and the rest of the plan writes itself around it.
Decide which one is the priority
If you want a faster ten kilometres, running leads: key sessions on fresh legs, strength fitted around them. If you want a bigger squat or a first pull-up, the order flips and the runs become the support work.
Write the priority at the top of the plan for the next eight weeks. When the two collide on a busy day, the priority wins and the other one gets shorter — it does not get skipped.
Separate your hard days
Put hard runs and heavy leg sessions on different days whenever possible. Two brutal sessions in one day is the fastest route to legs that feel flat for the rest of the week.
When you genuinely must combine them, do the priority first while you are fresh and make the second piece shorter or lighter. Running six kilometres after heavy squats and calling it "extra work" usually just damages both.
If you run in the morning and lift in the evening, keep the gap above eight hours when you can and make the lifting day the easier one.
Keep strength volume sane in run blocks
Two strength sessions a week are plenty while running matters: one full-body day and one shorter day for legs and hips. Squats, glute bridges, rows and presses — a few hard sets each, not ten.
In the last three days before a long run or a race, drop leg strength work entirely and keep only upper body. Heavy squats on Thursday do not make Saturday's long run better; they make it heavier.
Eat and sleep for two sports
Both training types draw from the same tank. Undereating to offset double sessions leaves you slower on the road and weaker in the gym, so eat like someone who trains twice a day, not like someone on a diet.
Sleep is where the adaptation actually happens. If the day cannot fit seven hours, cut a session rather than the sleep: a skipped session costs one workout, short sleep shows up in both sports.
Progress one thing at a time
Never increase weekly mileage and barbell weight in the same fortnight. Add distance or intensity to the runs for a block while strength simply maintains, then trade roles in the next block.
Log both side by side and check the trend once a month. Bulky keeps your runs and your lifts in the same diary, so you can spot the week where both numbers slid and add rest before the legs decide for you.