I mis-spent my youth with my best friend Jim Bonner: at uni we partied, DJ'ed and flew kites (or juggled) on beaches together; I visited him in Tokyo, where we went clubbing, record shopping and marathon-eating together.

Later in life we had kids at the same time - our sons were born within 24 hours of each other - set up two businesses together and did innumerable other projects together. He taught me so much and made me laugh even more.

Last year Jim died of complications from multiple myeloma, leaving behind Alex (my godson, 12), Melissa (10), and his wife Nana. Jim had a gruelling illness but bore it with humour and bravery. We all miss him massively.

I'm raising money to help start a fund for Alex and Melissa so they can have as much fun at university, on a year off, or in whatever way they want to, when they reach the same age as Jim and I were when we met.

I'm starting off with the middle-aged-man-in-lycra approach. On June 9th I'm taking part in a swim/run across and around Lake Windermere. 3km swim, 20km run. I'm doing it with a buddy from work who is basically half my age and coaches running for Nike. We will be tied together. It will be humiliating, exhausting and hard but nowhere near as gruelling as what Jim went through.

Many of you know Jim and have already contributed lots, and there is no pressure or expectation to do the same again. But the plan will be to invest the funds in a trust fund for Alex and Melissa that Jim set up when they were born.

I've set an aggressive target, but really anything you can donate would be much appreciated, and will help me find the extra motivation to get over the finish line.